Summary and Further Analysis of the Nearshore Reef Fishery of the N orthem Mariana Islands

Transcription

1 Summary and Further Analysis of the Nearshore Reef Fishery of the N orthem Mariana slands Prepared By: Michael S. Trianni Division offish and Wildlife Commonwealth of the Northern Mariana slands

2 TABLE OF CONTENTS LST OF FGURES....iv LST OF TABLES... vi ACKNOWLEDGEMENTS... vii EXECUTVE SUMMARY... viii NTRODUCTON... 1 METHODS... 1 Saipan and Tinian... 1 Northern slands... 5 ANALYSS... 5 RESULTS... 6 Species Composition... 6 Catch per Unit of Effort Length Frequency... 1 Holocentridae... 1 Serranidae... 6 Lutjanidae... 6 Caesionidae... 6 Lethrinidae... 6 Mullidae... 3 Kyphosidae... 3 Scaridae... 3 Acanthuridae Siganidae DSCUSSON Species Composition Catch per Unit of Effort Length Frequency CONCLUSON RECCOMENDATONS Reef Fish Market Sampling Surveys and Experiments Regulations REFERENCES... 49

3 APPENDX A APPENDX B... 63

4 LST OF FGURES FGURE 1. The Mariana Archipelago... FGURE. Saipan reef fishing zones....3 FGURE 3. Tinian reef fishing zones....4 FGURE 4. Percent composition by Family of reef fish from Saipan and Tinian....l5 FGURE 5. Percent composition by Family of reef fish from Anatahan & Sariguan FGURE 6. Percent composition by Family of reef fish from Agrihan & Maug FGURE 7. Composition of Parrot fish from Saipan, Tinian and the Northern slands 1995 & FGURE 8. Composition of Parrotfish from Saipan and Tinian from December 199 to February FGURE 9. Box-Whisker plot, ANOV A results and Tukey multiple range test for Myripristis berndti... 5 FGURE 1. Box-Whisker plot, ANOV A results and Tukey multiple range test for Epinephelus fasciatus... 7 FGURE 11. Box-Whisker plot, ANOV A results and Tukey multiple range test for Lutjanus kasmira... 8 FGURE 1. Box-Whisker plot of raw and log1 transformed fork length data for Lethrinus atkinsoni... :... 3 FGURE 13. Box-Whisker plot and ANOV A results on fork length( cm) for Parupeneus bifasciatus FGURE 14. Box-Whisker plot, ANOVA results and Tukey multiple range test for Acanthurus blochii FGURE 15. Box-Whisker plot, ANOV A results and Tukey multiple range test for Acanthurus lineatus FGURE 16. Box-Whisker plot, ANOV A results and Tukey multiple range test for Naso lituratus iv

5 FGURE 17. Box-Whisker plot, ANOVA results and Tukey multiple range test for Nasa unicarnis....4 v

6 LST OF TABLES TABLE 1. Sample size, mean length, standard deviation maximum and minimum length of reef fish from Anatahan... 7 TABLE. Sample size, mean length, standard deviation maximum and minimum length of reef fish from Sariguan... 9 TABLE 3. Sample size, mean length, standard deviation maximum and minimum length of reef fish from Central Fish MarkeL... 1 TABLE 4. Sample size, mean length, standard deviation maximum and minimum length of reef fish from Dar Corp....1 TABLE 5. Catch per unit of effort of reef fish from Saipan, Tinian, and Anatahan... TABLE 6. ANOVA results and Tukey tests on CPUE by year and location for Saipan and Tinian....3 TABLE 7. ANOV A results and Tukey tests on CPUE by year and location for Saipan and Tinian for the period January through March for 1993, 1994, and TABLE 8. ANOV A results and Tukey multiple range test on fork length by location for Pterocaesio tile and Gnathodentex aurolineatus... 9 TABLE 9. ANOV A results and Tukey tests on fork length for Lethrinus atkinsoni by year and location TABLE 1. ANOVA results and Tukey tests on fork length for Parupeneus barberinus and Mulloidichthys vanicolensis TABLE 11. ANOVA results and Tukey tests on fork length for Scarusforsteni and Scarus rubroviolaceus TABLE 1. ANOV A results and Tukey tests on fork length for Acanthurus nigricauda by year and location....4 TABLE 13. ANOV A results and Tukey tests on fork length for Siganus punctatus and Siganus argenteus V

7 ACKNOWLEDGEMENTS This project was fully funded by the U. S. Fish and Wildlife Service (USFWS) through the Dingell-Johnson (OJ) Sportfish Restoration Act. The support of the USFWS toward the goal of sustaining the fisheries resources of the Commonwealth of the Northern Mariana slands (CNM) is recognized and appreciated. The originators of this project, former CNM Division offish and Wildlife (DFW) Fisheries Biologists Mr. Tom Graham and Mr. John Gourley, are recognized for their efforts in conceiving and implementing the project. Mr. Graham is further accredited for producing DFW Technical Report 94-, the foundation upon which this report was produced. Former CNM DFW Fisheries Biologist Mr. Joseph Ostazeski resurrected this monitoring program and maintained the sampling protocol until his departure. Without his efforts this report would not have been possible. Mr. John Jordan of the CNM Office of Coastal Resources Management provided the digitized images of Saipan and Tinian. Of course the monitoring of fisheries is not achievable without the cooperation and support of the fishing companies. The owner of the Central Fish Market, Mr. Jack Castro, allowed us access to his reef fish catches from the Northern slands and provided us with landings data from non-sampled trips. The owners of the DAR Corp. graciously allowed us access to their personal residence before sunrise to sample the previous nights catch, and also provided us with invaluable catch-effort data for all their fishing trips. Vll

8 EXECUTVE SUMMARY Reef fish data obtained from market sampling during the period January 1995 through May 1996 from the Northern slands, Saipan, and Tinian are summarized and compared with data collected from Saipan and Tinian from February 1994 through March This last data set was summarized and analyzed in Division of Fish and Wildlife Technical Report 94-. Statistical analysis using ANOVA and t-tests revealed some trends in mean fish length between Saipan, Tinian, and the Northern slands. The same species from the Northern slands were larger than fish from Tinian and Saipan, and the same species from Tinian were generally larger than fish from Saipan. n some cases, significant statistical results in length by location for species of the family Scaridae could be attributed to significant differences in length between the terminal phase of the species, indicative of exploitation. Significant differences in catch per unit of effort were detected for Saipan and Tinian between collection periods and designated reef fishing zones. Fishing zone groupings varied slightly from those documented in DFW 94-, and followed expected patterns of fishing effort. Species composition data showed that families including Scaridae, Serranidae, and Lutjanidae from Saipan and Tinian were underrepresented in comparison to catches from the Northern slands. n addition, terminal phase Scaridae from Saipan and Tinian were underrepresented in comparison to Northern sland catches. Although notable differences were detected for mean length, species composition and catch per unit of effort, it was recommended that a comprehensive, long-term monitoring program be implemented to monitor the reef fish resources of the Commonwealth of the Northern Marianas slands. viii

9 ntroduction Data collected using U.S. Fish and Wildlife administered Dingell-Johnson (DJ) Sportfish Restoration Act funds under the job title 'Biological Analysis of the Nearshore Reef Fish Fishery' were initially summarized in Commonwealth of the Northern Mariana slands'(cnm) Division offish and Wildlife (DFW) Technical Report 94-, printed in April Data collection on the project was stopped following this report due to a lack of professional staff (CNM DFW 1995). Data were once again collected beginning in December 1995, but halted in May 1996 due to a lack of staff (CNM DFW 1996). This latter data set was collected from a vendor who graciously provided access to their catch, and diligently provided catch-effort data. Data from two trips was also collected from a second vendor in the month of November During the period January 1995 through July 1995, data were collected from a nearshore reef fishery operating out of Saipan in the islands of the CNM north of Farallon de Medinilla (Figure 1). This fishery centered primarily around the island of Anatahan, but extended as far north as the island of Maug. Although the fishery targeted primarily reef fish through the use of 'hookah' and SCUBA, trolling to and from fishing grounds, as well as insignificant bottomfishing, occurred. These latter data are not included in this report. This report summarizes and analyzes those data collected since DFW 94-, including data used in DFW 94- where appropriate. Methods Saipan and Tinian The majority of data were collected from one commercial spearfishing operation based in Saipan. This company was Filipino owned and operated, the DAR Corp., with all fishermen having been contract workers from the Philippines. All fishing occurred during nighttime hours off an 5 foot vessel utilizing SCUBA. Up to four dives were made per night. Fishermen changed during the study period, when two experienced individuals left in January 1996, and this may have effected catch rates (DFW 1996). t was also noted that some leakage was known to have occurred, although the amount was considered insignificant for the summary and analyses in this report. Two types of data were collected during the period. The first was catch-effort data, collected from December 1995 through May These data collection protocol followed the guidelines outlined in DFW 94-. A catch log was submitted to the manager of the Dar Corp., which was filled out following each nightly fishing trip. The primary data used in generation of Catch per Unit of Effort (CPUE) indices are listed on the catch log 'CNM Division offish and Wildlife Daily Fishing Log' in Appendix B. Figures & 3 show maps of the reef zones designated in DFW 94- for Saipan and Tinian. The catches of the fishing operation were sampled on a weekly basis from December 1995 through March Sampling was conducted on the premises of the DAR Corp, beginning about 53-6 following the previous nights fishing trip. The catch was brought to market at 7. During each sampling episode all fish were measure to the nearest millimeter fork length, identified to the specific level with phase recorded where appropriate. The DFW Fisheries Section had an open account for the purchase of fish not identifiable during the 1

10 Uracas Bank C Stingray Shoal o raess o Supply Reef r r t---oaug : "Asuncion _ _r _ _ i o Agrihan PPagan _ _r _ _ OAlamagan.. G,uguan _ _ _+--+_ Zealandia Bank o Sariguan C'Pathfinder Reef A narigan Bank = <::> Anatahan OSonome Reef G Arakane Reef Peligro Reefo a Farallon de edinilla Opakapaka Reef! Coke Reef r r t-----esmeralda Bank rj Saipan Tinian Aguijan BankA C) L? Rota r _ _ _ uam o Cocos r r t------'v::.."' Galvez Banks o Santa RosJ Reef Figure 1. The Mariana Archipelago.

11 West Saipan.. " ". -.;. '.: ".. Lagoon East Saipan South Saipan Figure. Saipan reef fishing zones. 3

12 East Tinian West Tinian Figure 3. Tinian reef fishing zones. 4

13 sampling time frame. References used for fish identification were; Allen (1987), Allen and Talbot (1985), Amesbury and Myers (198), Anderson (1987), Masuda et al. (1985), Myers (1991), Randall (1987), Randall et al. (199), Sainsbury et al. (1985), and Smith and Heemstra (1986). For species that did not have an established length-weight relationship, each fish was also weighed to the nearest tenth of a gram using 6 g and 1 g top loading digital Ohaus scales. During analysis lengths were converted to centimeters and weights to kilograms. Total weight was obtained from the manager of the DAR Corp.. Further details on the data collection procedure are found in DFW Some data were also available from the sampling of two Saipan catches by the Central Fish Market in November These data were obtained by spearfishing with SCUBA in a manner similar to that of the DAR Corp. Species composition and length-frequency data were available from these two samples. Northern slands Data collection procedures for the Northern slands reef fishery were conducted on the premises of the Central Fish Market following the vessels return from a trip. This company was locally owned and employed numerous Filipino and Sri Lankan fishermen. Spearfishing occurred off the main vessel, the JQC 1, a converted factory trawler approximately 65 feet long. One to two foot boats were deployed with three to four divers who utilized SCUBA and 'hookah'. Fishing effort varied and was not recorded by the vessel crew, although the captain of the vessel filled out a DFW catch-effort log for one trip to Anatahan. Landings data were provided to the DFW by Central Fish Market management personnel. These data were grouped in broad, non-systematic categories. Each sampled trip was sub-sampled due to the operational inability to whole-haul sample. The catch was transferred from the JQC 1 to the Central Fish Market via various sized baskets. t was then dumped into one of three large sinks where it was sorted and re-packed for refrigeration. Fish were chosen for sampling by selecting all the fish in a sink, or by basket selection. Length data were recorded as for the DAR Corp., while most weights were recorded to the nearest tenth of a gram using the appropriate Pensola spring scale. All sampled fish were identified to the specific level, and the DFW Fisheries Section had an open account for the purchase of fish not identifiable during the sampling time frame. Analysis One-way ANOVA's were employed to determine significant differences in species fork length to the nearest centimeter for specimens from Saipan, Tinian, and the Northern slands (Anatahan and Sariguan). Data were screened for normality using Box-Whisker plots. Because the ANOV A model is robust to even moderate deviations from normality (Hicks 198; Dowdy and Weardon 1991), it was subsequently used to test for differences in the response factor. f Box-Whisker plots indicated non-normality in a data set, the non-parametric Kruskal-Wallis test was also applied to verify significant differences found by ANOVA (Potvin and Roff, 1993). Multi-factor ANOVA test's were employed when insufficient data from the Northern slands precluded the one-way test. When Northern sland data were lacking, species length was 5

14 tested between Saipan and Tinian using the factors of 'Period' and 'Location'. Because all data sets were unbalanced with the number of observations for the different treatment combinations being unequal, the ANOV A tests were calculated using the Type Sum of Squares (Shaw and Mitchell-Olds, 1993). These data were also screened with Box-Whisker plots, and when nonnormal data were indicated, the data were transformed using 1gO. The factor "Period' contained two levels, one for the data set collected from December 199 to February 1994, and one for the data set collected from November 1995 to March 1996 (throughout this report period 'one' will identify the former time period, while period 'two' will identify the latter). The factor 'Location' contained two levels, data aggregated for both Saipan and Tinian. When data were available for only Saipan or Tinian and the Northern slands, then a t-test was employed, testing the null hypothesis that the fork length means were equal. For the Scaridae, t-tests were used to test for significant differences in location between initial phases, and between terminal phases. Following significant ANOVA main effects results, sites were grouped using Tukey's Honestly Significant Difference test, one of the more conservative multiple comparison procedures (Dowdy and Weardon 1991). The Tukey test protects the Type error rate by using a single error rate, or alpha level, for the entire experiment (Dowdy and Weardon 1991). f ANOV A results found significant interactions the Tukey test was not conducted because multiple comparison tests are designed to elucidate significant main effects only (Hicks 198). Catch per unit of effort was analyzed using the multi-factor design, with the factor 'period' having two levels (as above), and the factor 'location' having six levels defined as West Saipan, Saipan Lagoon, South Saipan, East Saipan, West Tinian, and East Tinian(Appendix B). Data from DFW 94- used in this analysis included data from January 1993 through March 1994, and only data collected from the Saipan Fishing Center were used because the methods employed were hookah and SCUBA. t was stated in a reference report (DFW 1994) that CPUE data used in DFW 94- were limited to the time period February 1993 though October 1993, which included primarily hookah fishing. Data collected from the Saipan Fishing Center after October 1993 included only SCUBA. Data collected from Diego's Market was not used because location codes recorded referred only to Saipan or Tinian, and the majority of these data were from free diving. Results Species composition Species composition tables were generated for the DAR Corp., the local Central Fish Market data, and the Northern slands data which was separated into catches from Anatahan and Sariguan (Tables 1-4). Comparison of Tables 1-4 shows a distinct difference in the composition of the dominant species landed between the Northern slands (Anatahan and Sariguan) by the JQC 1, and those landed in the Southern slands (Saipan and Tinian) by the DAR Corp. The top species landed by the Dar Corp. were composed primarily of the family Acanthuridae (Table 4, Figure 4), while Acanthurids comprised a much smaller percentage of reef fish landed from Anatahan and Sariguan (Tables 1 &, Figure 5). t is interesting to note that the sampled data in Table 1 shows a much smaller representation of the catch as Acanthurids, approximately 15%, compared to 3% depicted in Figure 5. The data used to produce the chart were from landings 6

15 Table 1. Sample size, mean length, standard deviation, maximum and minimum length of reef fish sampled from Central Fish Market catches at Anatahan, March July No.# trips sampled = 6. Species n Mean StdDev Max Min Myripristis berndti Scarus rubroviolaceus Pterocaesio tile Naso lituratus Parupeneus bifasciatus Caesio teres Lutjanus kasmira Epinephelus fasciatus Monotaxis grandoculus Sargocentron tiere Acanthurus blochii Gnathodentex aurolineatus Kyphosidae Macolor macularis Acanthurus lineatus Scarus forsteni Kyphosus cinerascens Sargocentron spiniferum Macolor niger Scarus microrhinos Cephalopholis argus Mulloidichthys vanicolensis Naso unicorn is Plectorhinchus picus Variola louti Acanthurus nigricauda Epinephelus tauvina Myripristis violacea Heteropriacanthus cruentatus Lutjanus gibbus Kyphosus bigibbus Neoniphon opercularis Xyrichtys pavo Aphareus furca Cetoscarus bicolor Oedalechilus labiosus Calotomus carolinus Lethrinus rubrioperculatus

16 Table 1. Continued. Species n Mean StdDev Max Min Kyphosus vaigiensis Parupeneus multifasciatus Myripristinae Siganus argenteus Acanthurus triostegus Caesio lunar is Caranx lugubris Caranx melampygus Cheilinus undulatus Lethrinus obsoletus Zebrasoma veliferum Cephalopholis sexmaculata Cephalopholis urodeta Epinephelus hexagonatus 1.6 Epinephelus macrospilos Lutjanus fu v us Myripristinae Naso hexacanthus 1 3. Oxycheilinus unifasciatus Parupeneus barberinoides Parupeneus cyclostomus Pterocaesio marri Saurida gracilis Scarus sordidus

17 Table. Sample size, mean length, standard deviation, maximum and minimum length ofreeffish sampled from Central Fish Market catches at Sariguan, February No. # sampled trips = 1. Species n Mean StdDcv Max Min Scarus rubroviolaceus Cephalopholis argus Parupeneus bifasciatus Acanthurus lineatus Variola louti Epinephelus socialis Acanthurus nigricauda Kyphosidae Naso lituratus Kyphosus cinerascens Monotaxis grandoculus Sargocentron spiniferum lfipposcaruslongiceps Oxycheilinus unifasciatus Plectorhinchus picus 3.3 9

18 Table 3. Sample size, mean length, standard deviation, maximum and minimum length of reef fish sampled from the Central Fish Market, Saipan. November No.# tips sampled = Species n Mean StdDev Max Min Acanthurus nigricuada Pterocaesio marri Gnathodentex aurolineatus Myripristis berndti Naso lituratus Lethrinus obsoletus Epinephelus fasciatus Parupeneus barberinus Mulloidichthys vanicolensis Parupeneus bifasciatus Lethrinidae Sargocentron tiere Scarus psittacus Myripristis adusta Pterocaesio tile Scarus globiceps Scar us sordidus Cephalopholis argus Lutjanus kasmira Scarus schlegeli Mulloidichthys flavolineatus Siganus punctatus Acanthurus olivaceus Heteropriacanthus cruentatus Lethrinus atkinsoni Epinephelus howlandi Monotaxis grandoculus Neoniphon opercularis Plectorhinchus picus Scarus microrhinos Variola louti Acanthurus pyroferus 1. Aphareus furca Caesio cuning Cetoscarus bicolor Lutjanus fulvus

19 Table 3. Continued. Species n Mean SfdDev Max Min Myripristis amaena Parupeneus pleurostigma 1.8 Sargocentron spiniferum

20 Table 4. Sample size, mean length, standard deviation, maximum and minimum length of reef fish sampled from the DAR Corp., December March No.# sampled trips = 11. Species n Mean StdDev Max Min Naso lituratus Naso unicornis Acanthurus lineatus Siganus argenteus Lethrinus atkinsoni Mulloidichthys vanicolensis Acanthurus nigricauda Parupeneus barberinus Scarus ghobban Siganus punctatus Parupeneus bifasciatus Acanthurus blochii Mulloidichthys javolineatus Scarus psittacus Lethrinus obsoletus Scarus sordidus Scar us schlegeli Myripristis berndti Hipposcarus longiceps Gnathodentex aurolineatus Epinephelus merra Parupeneus ciliatus Parupeneus multifasciatus Upeneus taeniopterus Heteropriacanthus cruentatus Scarus rubroviolaceus Sargocentron tiere Epinephelus hexagonatus Acanthurus xanthopterus Scaridae Epinephelus howlandi Kyphosus bigibbus Mullidae Myripristis amaena Pterocaesio tile Epinephelus polyphekadion

21 13 - Table 4. Continued. Species n Mean StdDev Max Min Monotaxis grandoculus Parupeneus cyclostomus Cheilinus trilobatus Lutjanus fulvus Cephalopholis argus Parupeneus pleurostigma Sargocentron spiniferum Acanthurus nigricuada Calotomus carolinus Cephalopholis urodeta Epinephelus fasciatus Kyphosus vaigiensis Sargocentron caudimaculatum Acanthurus olivaceus Lethrinidae Scarus globiceps Scarus microrhinos Aphareus furca Hemigymnus melapterus Lethrinus rubrioperculatus Lutjanus kasmira Scarus altipinnis Cheilinus chlorourus Epinephelus tauvina Kyphosus cinerascens Lethrinus harak Lethrinus olivaceus Macolor niger Myripristis murdjan Myripristis pralinia Myripristis violacea Naso vlamingii Plectorhinchus picus Scarus forsteni Scarus oviceps Acanthurus nigricans Acanthurus triostegus Ctenochaetus striatus

22 Table 4. Continued. Species n Mean StdDev Max Min Epibulus insidiator Gymnocranius n. sp Hemigymnus fasciatus 6.9 Lethrinus xanthoclius Macolor macularis 1.9 Mullidae(Mulloidichthys) Naso annulatus 51.7 Naso hexacanth us 5.8 Naso tuberosus Neoniphon opercularis Oplegnathus punctatus Oxycheilinus unifasciatus 7. Plectorhinchus orientalis 3.8 Variola louti 9.6 Zebrasoma veliferum.7 14

23 Acanthuridae 4% Siganidae 1% Holocentridae 15% Serranidae 6% Heteropriacanthidae 1% Scaridae 7% Mullidae 11% Caesionidae 15% Lethrinidae % Holocentridae 3% Siganidae 1% Serranidae 3% Lethrinidae 9% Mullidae 16% Other % Scaridae 11% Heteropriacanthidae 1% Lutjanidae 1% Acanthuridae 43% Figure 4. Percent composition by Family of reef fish landed from Saipan and Tinian by the Central Fish Market from November 1995(top, n = ), and the DAR Corp. from December March 1996(bottom, n = 11). 15

24 Acanthuridae 3% Carangidae 3 % Holocen tridae 17% Siganidae 1% Kyphosidae 3% Labridae 3% Lethrinidae 8% Serranidae 13% Haemulidae % Scaridae 17% Lutjanidae 4% Mullidae 4 % Acanthuridae 8% Carangidae 5% Holocentridae 13% Kyphosidae % Lethrinidae 6% Serranidae 14% Lutjanidae 1% Haemulidae 5% Scaridae 13% % Figure 5. Percent composition by Family of reef fish landed from Anatahan(top, n = 7), and Sariguan(bottom, n = 3) by the Central Fish Market in

25 data provided by the company. s not determinable whether the Acanthurids were underrepresented in the samples taken, or the company data was an over-estimation of the actual catch. Data in Table 3 and Figure 4 of Saipan reef fish sampled from the Central Fish Market show a similar composition to those landed from Anatahan and Sariguan (Tables 1 &, Figure 5). This may have been due to a company preference for certain species or families of fish. The top species landed from DFW 94- were Acanthuridae (4.8%), Scaridae (%), Lethrinidae (7.6%), Mullidae (6.1%), Holocentridae (4.5%) Siganidae (4.%), Serranidae (4.4%), Lutjanidae (%), and Heteropriacanthidae (1.%) (Appendix 5..3 ofdfw 94-). The dominant species landed at night from that study are similar to those sampled from the catches of the DAR Corp.. n particular, the percentage of Acanthurids landed between the two periods, one and two, were identical (Figure 4). The percentage ofscarids was lower from the period two data, while the percentage ofsiganids was larger, as was the percentage of Mullidae. The percentages landed from the remaining five families were similar. A notable difference in the compositions from the Southern slands as compared to those from the Northern slands was the low percentages of the family Serranidae in the former. Groupers comprised from 13% to 19% of the estimated Northern sland landings (Figures 5 & 6), while in the Southern slands Serranids comprised 6% of the catch from the Central Fish Market and 3% of the catch from the Dar Corp. (Figure 4). The sampled data for Anatahan consists of approximately 7% Serranids, and for Sariguan 8% (Tables 1 & ). The percentages of catch for the family Scaridae were lower in the data collected from the Southern slands as compared to the landings data reported from the Northern slands. The sampled data from Anatahan consisted of approximately 13% Scaridae, as did the data supplied by the Central Fish Market (Table 1 and Figure 5). For Sariguan, the percentages were 8% from the sampled data and 13% from the company data (Table and Figure 5). The parrotfish Scarus rubroviolaceous was a dominant representative of the Scaridae composition sampled from the Northern slands (Figure 7), and in catches from Saipan and Tinian during period one (Figure 8 & Appendix 5..1 ofdfw 94-). This species was not a dominant representative of the scarids landed in the Southern slands by the DAR Corp. or the Central Fish Market from period two (Tables 3 & 4; Figure 7). This species is found throughout the Mariana slands (DFW 1998; DFW 1987; Amesbury 1984). t is probably the most abundant Scarid in the Northern slands as it favors boulder-strewn slopes of high-island cliffs (Meyers 1991), a common habitat type in that region (DFW 1987). The percentage of terminal phase males versus initial phase scarids was examined between the Northern and Southern slands. The percentage of terminal phase Scarids sampled from the Northern slands was 78%. The percentage of terminal phase Scarids sampled from the Southern slands was 66% from period one (DFW 1994), and 5% from period two. Comparing Saipan and Tinian, in period one the percentage of terminal phase males was 61 % (n = 595) and 68% (n = 64), respectively, and from period two was 48%(n = 1), and 53%(n = 17), respectively. Catch per Unit of Effort The CPUE of nearshore reef fish for Saipan and Tinian was first examined in DFW 94- (DFW 1994). That technical report grouped night fishing per fishing effort zone, defined as West Saipan, Saipan Lagoon, South Saipan, East Saipan, West Tinian, and East Tinian (Figures 1 & ). The groupings in DFW 94- showed the lagoon CPUE to be significantly lower than 17

26 Acanthuridae 3% Carangidae 5% Holocentridae 9% Kyphosidae 9% Serranidae 15% Lethrinidae % Scaridae 18% Lutjanidae 1% Scaridae 3% Mulgidae 1% Serranidae 19% Mullidae 1% Lethrinidae 6% Siganidae 1% Kyphosidae 4% Holocentridae 6% Carangidae 6% Acanthuridae 3% Figure 6. Percent composition by Family of reef fish landed from Agrihan(top, n = 1) and Maug(bottom, n;' 1) by the Central Fish Market in

27 Scarus sordidus 16% Scarus micro rhinos % Scarus ghobban 6% Scarus forsteni 1% Scarus rubroviolaceus 7% Calotomus carolinus % Cetoscarus bicolor 1% Hipposcarus longiceps 9% Scarus altipinnis 1/ Scarus schlegeli 15% Scarus oviceps 1% Scarus globiceps 4% Scarus psittacus 16% Scarus rubroviolaceus 75% Cetoscarus bicolor % Scarus forstcni 13% Scarus sordidus 1% Scarus microrhinos 7% Calotomus carolinus % Figure 7. TOP: Composition of Parrot fish landed by the DAR Corp. and the Central Fish Market from Saipan and Tinian from November 1995 to March 1996 (n = 5). BOTTOM: Composition of Parrotfish landed from the Northern slands by the Central Fish Market from January to July 1995 (n = 314). 19

28 Scarus n. spp. 1% Scarus schlegeli 15% Scarus festivus 1% Scarus sordidus 16% Scarus rubrioviolaceus 15% Scarus frontinalis 1% Scarus oviceps 1% Scarus psittacus 16% Scarus 5% Scarus globiceps 3% Scarus altipinnus 3% Scarus ghobban 5% Scarus spp. 1% Scarus forsteni 5% Calotomus carolinus 3% Cetoscarus bicolor 1% Hipposcarus longiceps 9% Figure 8. Composition of Parrotfish landed from Saipan and Tinian from December 199 to February 1994 (n = 199).

29 both Tinian areas and the East Saipan area. The South Saipan and West Saipan CPUE were grouped with the Tinian CPUE's, but significantly lower than the East Saipan CPUE. t was noted that sample sizes were low from the South and East Saipan zones. The CPUE from three time periods are shown in Table 5. These periods were demarcated as January 1993 through December 1993, January 1994 through March 1994, and from December 1995 through May The data in Table 5 show a marked decline in CPUE over time. To test this difference, a multi-factor ANOVA was used to test time period with two levels and location with the six levels as described above. The time periods that included January 1993 though March 1994 were grouped as a single period (period one). A t-test was conducted on data from the period January 1993 through December 1993, comparing SCUBA versus hookah for West Saipan to determine if significant differences existed (Sufficient data existed only from West Saipan). The purpose was to determine whether or not these two methods could be grouped together for further analysis using ANOV A, that is, whether data from 1994 could be grouped with data from The test did not produce a significant difference (t! = 1.57, p-value =.13; SCUBA, n = 3 & hookah, n = 3), and data were grouped. The ANOVA detected significant differences with respect to period and location code, with an insignificant interaction (Table 6). The CPUE of the second time period was significantly lower than the first time period. The addition of the CPUE data from the second time period resulted in a more complicated grouping of fishing zones (Table 6). South Saipan, West Saipan, and Saipan Lagoon were still grouped together. South Saipan, West Saipan, and West Tinian were grouped together, West Tinian and East Tinian, and East Tinian and East Saipan (Table 6). The differences from the groupings reported in DFW 94- were that the only Saipan zone the East Tinian zone was grouped with was East Saipan, the latter of which was no longer grouped with the West Tinian zone. Due to the discrepancies in the duration of the time periods tested (14 for period one and 6 for period two), data collected from January through March from 1993, 1994, and 1996 were tested to determine if seasonality had an effect on the above results. The data were grouped by two factors, 'Year' and 'Location', with three and two(saipan and Tinian) levels respectively. Table 7 shows the results of this analysis. A significant difference was found for 'Location' with Tinian CPUE being larger than Saipan CPUE. Also, a significant difference was found for 'Year', with data from 1993 and 1994 grouped together and were significantly greater than data from No significant interaction resulted. Because this test yielded similar results it was concluded that seasonality had no effect on the previous ANOV A. Length Frequency Length frequency histograms for select species comparison between the Southern (Tinian & Saipan), and Northern (Anatahan & Sariguan) slands are listed in Appendix A. Sufficient data from both regions was not available for histogram comparisons for most species. Results from ANOV A and t-tests are listed below phylogenetically by family group. Holocentridae The Box-Whisker plot for Myripristis berndti indicated non-normality in the data set (Figure 9). The one-way ANOV A for fork length by location for M berndti detected a highly significant difference (Table X; KW test statistic = 98.5, p-value =.). Fish from the 1

30 Table 5. Catch per unit of effort (CPUE) of reef fish from Saipan and Tinian, and from Anatahan in Data are from night fishing. Each sample is equal to one night of fishing. Standard deviation is in parenthesis. Location *1993 **1994 ***1996 n CPUE n CPUE n CPUE West Saipan (3.8) (3.8) 36 Lagoon 5 1.8(3.3) 1 11.(.) 37 South Saipan 3 1.7(3.8) East Saipan (4.7) Saipan Mean 1.(3.8) 1.(3.5) Tinian West (3.8) 5 8.1(.7) 4 Tinian East (6.1) (4.7) 9 Tinian Mean 13.8(4.5) 1.5(4.7) Overall Mean 1.9(4.3) 1.3(3.7) ****Anatahan 3 8.6(.8) 7.(.3) 7.4(.4) 13.(7.4) 8.(3.) 9.7(4.4) 9.(3.3) 9.5(4.1) 8.6(3.5) 9.6(1.4) * - Data from January 1993 through December 1993, collected from the Saipan Fishing Center and Diego's Mart. ** *** **** - Data from January 1994 through March 1994, collected from the Saipan Fishing Center and Diego's Mart. - Data from December 1995 through May 1996, collected from the DAR Corp. -Data from two trips, in March and April of 1995.

31 Table 6. ANOV A results and Tukey tests on CPUE by year and location for Saipan and Tinian. Source Df Mean Square F-Ratio P-Value MAN EFFECTS A:Year B:Location NTERACTONS AB RESDUAL ************************************************************************* Multiple Range Tests for CPUE by Year Method: 95. percent Tukey HSD Year Count LS Mean Homogeneous Groups x X ************************************************************************* Multiple Range Tests for CPUE by Location Method: 95. percent Tukey HSD LocCode Count LS Mean Homogeneous Groups :xx X :xx XX XX X 1 = West Saipan; = Saipan Lagoon; 3 = South Saipan; 4 - East Saipan; 5 = West Tinian; 6 = East Tinian 3

32 Table 7. ANOVA results and Tukey tests on CPUE by year and location for Saipan and Tinian for the period January through March for 1993, 1994, and Source Of Mean Square F-Ratio P-Value MAN EFFECTS A:Locale B:Year NTERACTONS AB RESDUAL *********************************************************************** Multiple Range Tests for CPUE by Year Method: 95. percent Tukey HSO Year 3 1 Count LS Mean Homogeneous Groups 1 = Jan through March 1993; = Jan through March 1994; 3 = Jan through March 1996 *********************************************************************** Multiple Range Tests for CPUE by Locale Method: 95. percent Tukey HSO x X X Locale Count LS Mean Homogeneous Groups = Saipan; = Tinian X X 4

33 Location Code Fork Length(cm) Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************ Multiple Range Tests for FLCM by Location Code Method: 95. percent Tukey HSD LoCode Count Mean Homogeneous Groups = Saipan = Tinian 3 = Northern slands x X X Figure 9. Box-Whisker plot, ANOVA results, and Tukey multiple range test for Myripristis berndti. 5

34 Northern slands were significantly larger than fish from Tinian, which were significantly larger than fish from Saipan. M. berndti is the largest and one of the more common holocentrids found throughout the Mariana slands (DFW 1998; DFW 1987). t was a dominant species found in the catches of reef fish from the Northern slands, and the dominant holocentrid found in reef fish catches from the Southern slands (Tables 1,3 & 4). Serranidae The Box-Whisker plot for Epinephelus fasciatus indicated non-normality, and the oneway ANOVA detected a highly significant difference by location (Figure 1; KW test statistic = 54.8, p-value =.). Northern sland fish were found to be significantly larger than Tinian and Saipan fish, which grouped together. Although primarily found on the outer reef slope, this species can be found in shallow depths in lagoons up to 4 meters (Myers 1991). t is a major constituent of the shallow water bottomfish complex (6-1 meters), but is also found in spearfish catches. The species is found throughout the Mariana slands (DFW 1998; DFW 1984). Lutjanidae A Box-Whisker plot did not indicate non-normality in the data set for Lutjanus kasmira. The one-way ANOV A for fork length by location for L. kasmira detected a significant difference, and the Kruskal-Wallis test was conducted (Figure 11; KW test statistic = 46.4, p value =.). Fish from the Northern slands were found to be significantly larger than fish from Tinian and Saipan. The latter data sets consisted of small sample sizes that may have influenced results. This species is common throughout the Marianas (DFW 1998). Cacsionidae The one-way ANOV A for fork length by location for Pterocaesio tile detected a highly significant difference (Table 8). Fish from Saipan were significantly larger than fish from the Northern slands, which in tum were significantly larger than fish from Tinian. A very small sample size from the Saipan group may have influenced these results. This species is found throughout the Mariana slands (DFW 1998). Lcthrinidae A one-way ANOVA was conducted on fork length by location for Gnathodentex aurolineatus. A significant difference was detected, with Northern sland fish being larger than those from the Southern sland group, and Tinian fish being larger than those from Saipan (Table 8). This species is common throughout the Mariana slands, often observed in large schools over coral flats and ravines (Myers 1991; Amesbury 1984; DFW 1987). A Box-Whisker plot for Lethrinus atkinsoni indicated non-normality and the data were transformed using OglO (Figure 1). A multi-factor ANOVA was performed on fork length for L. atkinsoni with significant differences detected for both period and location (Table 9). Tinian fish were larger than Saipan fish, and fish in period two were larger than fish in period one. Although Myers (1991) describes this species as 'relatively uncommon' in the Mariana slands, 6

35 r-r- Location 1 - (J + Code Fork Length(cm) Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************ Multiple Range Tests for FLMM by Location Method: 95. percent Tukey HSD Location Count Mean Homogeneous Groups = Saipan = Tinian 3 = Northern slands ************************************************************************ x X X Figure 1. Box-Whisker plot, ANOV A results, and Tukey multiple range test for Epinephelus fasciatus. 7

36 Location Code H 3 ' Fork Length(cm) Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************ Multiple Range Tests for FLCM by LocCode Method: 95. percent LSD LocCode Count Mean Homogeneous Groups x X X 1 = Saipan = Tinian 3 = Northern slands Figure 11. Box-Whisker plot, ANOVA results, and Tukey multiple range test for Lutjanus kasmira. 8

37 Table 8. ANOV A results and Tukey multiple range test on fork length( cm) by location for Pterocaesio ti/e(top), and Gnathodentex aurolineatus(bottom). Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************** Multiple Range Tests for FLCM by Location Code Method: 95. percent Tukey HSD LoCode Count Mean Homogeneous Groups = Saipan = Tinian 3 = Northern slands x x X Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************** Multiple Range Tests for FLCM by LoCode Method: 95. percent Tukey HSD LoCode Count Mean = Saipan = Tinian 3 = Northern slands Homogeneous Groups X X X 9

38 Location Code + [ljp, + -,' Fork Lcngth( cm) Location Code 1 -. '-f L ['L..,, LoglO Transformed Fork Length(cm) Figure 1. Box-Whisker plots ofraw(top) and loglo transformed(bottom) fork length data for Lethrinus atkinsoni. 3

39 Table 9. ANOVA results and Tukey tests on fork length(cm) for Lethrinus atkinsoni by year and location('year' is equivalent to two distinct sampling periods-see Tukey test). Source Df Mean Square F-Ratio P-Value MAN EFFECTS A: Year B:LoCode NTERACTONS AB RESDUAL ************************************************************************** Multiple Range Tests for FLCM by LoCode Method: 95. percent Tukey HSD LoCode Count LS Mean Homogeneous Groups = Saipan = Tinian x X ************************************************************************** Multiple Range Tests for FLCM by Year Method: 95. percent Tukey HSD Year Count LS Mean Homogeneous Groups X X 1 = December February 1994 = November March

40 it was, along with G. aurolineatus, one of the two dominant lethrinids taken during night fishing operations (DFW 1994; Table 4). The species favors sea grass beds and sandy areas of lagoons and outer reef slopes (Myers 1991), habitats characteristic of the Southern slands. Mullidae Multi-factor ANOVA's were conducted on fork length by period and location for Parupeneus barberinus and Mulloidichthys vanicolensis. A significant difference was detected for location for P. barberinus, with Tinian fish being significantly larger than Saipan fish (Table 1). A significant difference was also detected for M vanicolensis, but a significant interaction precluded the multiple range test. Data for P. bifasciatus were screened with Box Whisker plots and non-normality was indicated(figure 13). A non-significant difference was found by location, although the results were marginal. Consequently, the data were subjected to a Kruskal-Wallis test, with the results also being marginally non-significant (KW test statistic = 4.81, p-value =.9). P. barberinus and M vanicolensis favor sandy areas of lagoons and outer reef slopes, where they feed on sand dwelling invertebrates (Myers 1991). These fish appear to be more abundant in the Southern slands, while P. bifasciatus is common throughout the Mariana slands (DFW 1998; Amesbury 1984, DFW 1987). Kyphosidae A t-test was conducted on Kyphosus cinerascens comparing fish from Tinian and the Northern slands. No significant difference in fork length was detected t! =.8, p-value =.94). Scaridae One-way ANOV A tests on fork length by location were conducted for Scarus forsteni and S. rubroviolaceus. Significant differences for location resulted for both species. For S. forsteni ANOVA results showed that significant differences were found between locations (Table 11). Saipan and Tinian fish grouped together, as did Saipan and Northern sland fish. A t-test revealed that terminal phase fish from the Northern slands were not significantly larger than fish from the Southern slands (t! =.77, p-value =.391; n = 4 & n = 43). A t test for initial phase fish showed that those from the Northern slands were marginally significantly larger than those from the Southern slands although the Northern sland sample size was very small (t! = 1.949, p-value =.56; n = 4 & n = 6). The failure of the t-test to detect differences as significant as the ANOVA was a result of the groupings as indicated by the Tukey test. For S. rubroviolaceus ANOVA results and the Tukey test showed that Northern sland fish were significantly different from Tinian and Saipan fish (Table 11). A t-test revealed that initial phase fish from the Northern slands were not significantly larger than fish from the Southern slands (t! =.395, p-value =.346; n = 8 & n = 48). A t-test for terminal phase fish showed that those from the Northern slands were significantly larger than fish from the Southern slands (t! =.89, p-value =.; n = 164 & n = 14). 3

41 Table 1. ANOVA results and Tukey tests on fork length(cm) for Parupeneus barberinus(top), and Mulloidichthys vanicolensis(bottom) by year and location('year' is equivalent to two distinct sampling periods-see Tukey test). Source Df Mean Square F -Ratio P-Value MAN EFFECTS A: Year B:LocCode NTERACTONS AB RESDUAL *************************************************************************** Multiple Range Tests for FLCM by LoCode Method: 95. percent Tukey HSD LoCode Count LS Mean Homogeneous Groups = Saipan = Tinian x X Source Df Mean Square F -Ratio P-Value MAN EFFECTS A:Year B:LocCode NTERACTONS AB RESDUAL

42 Location Code + [] D 3 + ODD D D Fork Length(cm) 8 31 Source Df Mean Square F-Ratio P-Value Between groups Within groups Figure 13. Box-Whisker plot and ANOVA results on fork length(cm) for Parupeneus bifasciatus. 34

43 Table 11. ANOVA results and Tukey test on fork length(cm) by location for Scarus /orsteni(top), and Scarus rubroviolaceus (bottom). Source Df Mean Square F -Ratio P-value Between groups Within groups ************************************************************************* Multiple Range Tests for FLCM by LoCode Method: 95. percent Tukey HSD LoCode Count Mean Homogeneous Groups X XX X 1 = Saipan = Tinian 3 = Northern slands Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************* Multiple Range Tests for FLCM by LoCode Method: 95. percent Tukey HSD LoCode Count Mean Homogeneous Groups = Saipan = Tinian 3 = Northern slands X X X 35

44 Due to small sample sizes from Tinian for period two, t-tests were used to test the hypotheses that Tinian fish were larger than fish from Saipan for Scarus schlegei, S. psittacus and S. sordidus.. For S. schlegeii, the t-test showed that fish from Tinian were significantly larger than fish from Saipan (t! = 5.15, p-value =.; n =13 & n =17). A t-test on initial phase fish showed that those from Tinian were significantly larger than fish from Saipan (t! = 5.46, p value =.; n = 53 & n = 7). A test for terminal phase fish showed those from Tinian to be significantly larger than those from Saipan (t! = 7.91, p-value =.; n = 7 & n =1). For S. psittacus, a t-test for the hypothesis that Tinian fish were larger than Saipan fish resulted in a highly significant difference (t! = 4., p-value =.; n = 17, n = 13). A similar test for initial phase fish showed that Tinian fish were not significantly larger than fish from Saipan (t! = 1.7, p-value =.85; n =1 & n =8). A t-test for terminal phase fish showed that Tinian fish were significantly larger than Saipan fish (t! = 4.41, p-value =.; n =117 & n = 14). For S. sordidus the t-test conducted on fork length between Tinian and Saipan showed Tinian fish to be significantly larger than Saipan fish (t! = 4.11, p-value =.; n = 177, n = 134). Testing the hypothesis that initial phase Tinian fish were significantly larger than initial phase Saipan fish resulted in non-significance.(/t! =.848, p-value =.199; n =49, n = 16). The hypothesis that terminal phase Tinian fish were significantly larger than terminal phase Saipan fish was highly significant (t! = 7.53, p-value =.; n =18, n = 116). The juveniles of this species school on exposed lagoon and reef flat areas (Myers 1991), and are frequently encountered in Saipan Lagoon (pers. obs). This species was rarely encountered in Northern sland reef fish surveys (Amesbury 1984; DFW 1987). Data for Scarus ghobban were limited to one location, but were present from both time periods. This species favors shallow lagoon and seaward reefs, typically near soft sediment areas (Myers 1991). This may explain the limited location data available for this species, which was not encountered during Northern sland reef fish surveys (Amesbury 1984; DFW 1987). At-test showed no significant difference in fork length between periods (t! =.41, p-value =.674). Acanthuridae One-way ANOVA tests on fork length by location were conducted for Acanthurus blochii, Acanthurus lineatus, Naso lituratus and Naso unicornis. Significant differences for location resulted for all four species. Because Box-Whisker plots indicated non-normality in the data for all four species, the non-parametric Kruskal-Wallis(KW) test was also used to test for significance in the response factor. For A. blochii, Tinian and Northern sland fish grouped together and were significantly larger than the Saipan fish (Figure 14; KW test statistic = 14.4, p-value =.). For A. lineatus, Northern sland fish were found to be significantly larger than fish from Tinian and Saipan (Figure 15; KW test statistic = 83.3, p-value =.). This species is very common in the surge zone. One-way ANOVA results detected significant differences by location for N lituratus, with Northern sland fish being significantly larger than Tinian fish, which in turn were significantly larger than Saipan fish (Figure 16; KW test statistic = 199.6, p-value =.). Significant differences by location also were found for N unicornis, with Tinian fish being significantly larger than Northern sland and Saipan fish (Figure 17; KW test statistic = 18.3, 36

45 Location Code + : [,..-J 3 H- +H R '--, Fork Length(cm) Source Between groups Within groups Df 19 Mean Square F-Ratio P-Value ************************************************************************ Multiple Range Tests for FLCM by LoCode Method: 95. percent Tukey HSD LoCode Count Mean = Saipan = Tinian 3 = Northern slands Homogeneous Groups x X X Figure 14. Box-Whisker plot, ANOVA results and Tukey multiple range test on fork length(cm) for Acanthurus blochii. 37

46 Location Code -,- f- f ' ' Fork length(cm) = ft- f----l e Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************ Multiple Range Tests for FLCM by LocCode Method: 95. percent Tukey HSD LocCode Count Mean Homogeneous Groups x X X 1 = Saipan = Tinian 3 = Northern slands Figure 15. Box-Whisker plot, ANOV A results and Tukey multiple range test on fork length(cm) for Acanthurus lineatus. 38

47 Location Code H- OD ' Fork Length(cm) Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************** Multiple Range Tests for FLCM by LocCode Method: 95. percent Tukey HSD LocCode 1 3 Count Mean Homogeneous Groups x X X 1 = Saipan = Tinian 3 = Northern slands Figure 16. Box-Whisker plot, ANa VA results and Tukey multiple range test on fork length(cm) for Naso lituratus. 39

48 Location Code rno fben Fork Length( cm) Source Df Mean Square F-Ratio P-Value Between groups Within groups ************************************************************************ Multiple Range Tests for FLCM by Location Code Method: 95. percent Tukey HSD LoCode Count Mean Homogeneous Groups X X X 1 = Saipan = Tinian 3 = Northern slands Figure 17. Box-Whisker plot, ANOV A results and Tukey test on fork length( em) for Nasa unicarnis. 4

49 p-value =.). The Northern sland data set was very small for N unicornis, potentially confounding results. A multi-factor ANOV A on fork length by period and location was conducted for Acanthurus nigricauda. Significant differences were found for both main effects, with fish from period two being larger than those from period one, and fish from Saipan being larger than fish from Tinian (Table 1). Siganidae Multi-factor ANOV A tests were conducted on fork length by period and location for Siganus punctatus and Siganus argenteus. For S. punctatus, significant differences were found for both main effects, but a significant interaction precluded the multiple range tests(table 13). For S. argenteus a significant difference was found for location with period two fish being larger than period one fish, although a marginally significant interaction was found(table 13) Both species are more commonly encountered in the Southern slands (Amesbury 1984; DFW 987), although S. punctatus is listed as uncommon throughout the Marianas by Myers (1991). Discussion Species composition The relative equity of the percentages of families landed between period one and period two data, in particular the Acanthurids signifies that the target species of the two companies were similar. The low percentages of Scarids landed during period two versus period one (11 % & %, respectively), coupled with the decrease in the percentage of terminal phase males from period one (66%) to period two (5%) indicates that this family is a primary target species. t is notable that the percentage of terminal phase fish landed from Saipan was slightly lower than that from Tinian for both periods one and two. The comparison of the percentage of terminal phase males from both period one and period two against the percentage of terminal phase males from the Northern slands (78%) suggests that the species may be in decline in the Southern slands. The difference in the species composition of the Scarids from the Southern and Northern slands precludes the persuasiveness of this argument, although the decrease in the percentage of terminal phase males may have significance. n the family Scaridae terminal phase males are derived from females. Breeding males may also exist in the primary phase for some species (Thresher 1984). Terminal phase males pair spawn, whereas primary phase males group spawn (Thresher 1984). Pair spawning can be assumed to have a higher probability of successful gamete fertilization than group spawning. f terminal phase males are more susceptible to harvest than primary phase individuals, the difference in spawning behavior may effect recruitment success that may in tum exacerbate the effects of over-exploitation. A significant distinction in family composition between the Southern and Northern sland data was the low percentage of the family Serranidae present in catches from the Southern slands, 3%-6% versus 13-19% (Figures 4-6 and Results). 41

50 Table 1. ANOVA results and Tukey tests on fork length(cm) for Acanthurus nigricauda by year and location('year' is equivalent to two distinct sampling periods-see Tukey test). Source Df Mean Square F-Ratio P-Value MAN EFFECTS A:Year 3:LocCode NTERACTONS A RESDUAL **************************************************************************** Multiple Range Tests for FLCM by LoCode Method: 95. percent Tukey HSD LoCode Count LS Mean Homogeneous Groups = Saipan = Tinian x X ************************************************************************** Multiple Range Tests for FLCM by Year Method: 95. percent Tukey HSD Year Count LS Mean Homogeneous Groups X X 1 = December February 1994 = November March

51 Table 13. ANOVA results and Tukey tests on fork length(cm) by year and location for Siganus punctatus (top) and Siganus argenteus (bottom) ('year' is equivalent to two distinct sampling periods-see Tukey test). Source Of Mean Square F-Ratio P-Value MAN EFFECTS A:Year B:LoCode' NTERACTONS AB RESDUAL Source Df Mean Square F-Ratio P-Value MAN EFFECTS A:Ycar B:LoCode NTERACTONS AB RESDUAL *************************************************************************** Multiple Range Tests for FLCM by Year Method: 95. percent Tukey HSD Year 1 Count 5 36 LS Mean Homogeneous Groups x X 1 = December February 1994 = November March

52 As in the family Scaridae, Serranids are hermaphroditic, with breeding males being derived from females. These larger males may be preferential targets due to their size and aggressive behavior (Myers 1991). t appears as though grouper sex ratios are biased toward females, and the over-exploitation of larger size classes may therefore increase sex ratio bias, and potentially decrease successful spawning and subsequent recruitment (Myers 1991; Shapiro 1987). There were also a higher percentage of snappers (Lutjanidae) landed from the Northern slands. Snappers were observed in low percentages, or not at all in catches from Saipan and Tinian. Catch per Unit of Effort The significant change in CPUE from period one to period two indicates that overfishing had occurred, although the data from Anatahan in Table 5 is not much different from the mean for The catch-effort data from Anatahan may not have been collected in the same manner as those data from Saipan. Vessel personnel of the JQC 1 did not, prior to providing the DFW with the documented data, furnish the DFW with such data, and did not subsequently. The use of CPUE between time periods from different fishing companies does not take into account differences in species preference. Although CPUE was corrected for influential variables in the DFW 94- report, these same variables were not collected in the period two survey and therefore the CPUE from period one that was used in this analysis were the unadjusted CPUE. Two of the variables used for CPUE adjustment in 94- were 'hours' and 'spears', which are used in the estimation of CPUE, and are therefore correlated with CPUE. The CPUE from period one also included octopus and squid, the landings of which were not accounted for in period two data. Data on squid and octopus were not found when reviewing the computer files from the period one study, nor were they documented in DFW 94-. What influence these landings had on CPUE was not discernable. n addition to the measurement and determination of selected variables on CPUE, DFW 94- raised two other important issues with regard to CPUE. The first was that the low values from Saipan Lagoon were due to the possibility that fishing occurred there during periods of rough weather, in which case fishing would be less than optimal. This fishing behavior was documented from two sampled catches during period two, which lends merit to the supposition. The second issue was the impact of market forces on species selection and CPUE. t was noted in 94- that when the market for A. lineatus "became glutted" the species was intentionally avoided. This was not observed for any species during the collection of period two data. There is no doubt that market forces exert an impact on the selection of species, especially in a fishery such as spearfishing with SCUBA or hookah, which has selective potential. ncorporating such a variable into the generation of CPUE would prove beneficial. Groupings from the significant difference found in ANOV A for location follow what would be expected for exploitation in the six zones, with the possible exception of the South Saipan zone. This zone, which receives considerable fishing effort, had a small sample size, although the area fished is relatively small (Figure ). The East sides of both Saipan and Tinian yielded the highest least squares means and were grouped together. The east aspects of these islands are exposed to significant wave energy, making effort there sporadic. The primary areas for fishing, based on sample size are the lee 44

53 aspects ofsaipan and Tinian; West Saipan, Saipan Lagoon, and West Tinian (Table 6; Figures & 3). The value of the comparison ofcpue between time periods of varying length, from different vendors with potentially dissimilar fishing techniques and market biases, and possible confounding caused by the mixing of data generated from two dissimilar methods, can be questioned. The non-significance found between West Saipan CPUE collected by SCUBA and hookah during the period January 1993 though December 1993 alleviates concern in using data from two similar, though differing methods. The actual fishing techniques used would be more dependent upon the experience of the fishers, as the actual equipment employed would be similar. The variation between expert and non-expert fishers would be difficult to capture. The mere fact that an individual fishes at night to depths of 8 feet requires physical attributes which would be similar across nearly all fishers, although the efficiency and experience of optimizing ones time at depth is obviously a learned ability. Time spent fishing is invariably recorded as a rounded integer, thereby masking variation. Collection of such data specifically is not possible without participation by an observer. As stated above, the role market forces play in species preference and the potential affect on CPUE could be determined to some extent through a specific economic analysis of the reef fish market. The use of data from periods of varying length is problematic when one period is significantly shorter than another period. The ANOV A test on similar time frames from 1993, 1994, and 1996 yielded significant differences, particularly with respect to the factor 'Year', which suggested that seasonality did not significantly influence the results of the ANOVA on unequal time frames. Length Frequency Analysis of length frequency data between the Southern and Northern slands revealed a trend that Northern sland fish were significantly larger. This was the case for M berndti, E. fasciatus, L. kasmira, G. aurolineatus, (potentially P. bijasciatus,), S. rubroviolaceus, S. forsteni (N grouped with Tinian), A. blochii (N and Tinian grouped), A. lineatus, N. lituratus, (N. unicornis Tinian fish larger than N & Saipan). A t-test revealed no differences in length for K. cinerascens between Tinian and the Northern slands. Analysis of length frequency data from the Southern slands between Saipan and Tinian revealed a trend. Results oft-tests showed that Tinian fish were larger than fish from Saipan for the following species; L. atkinsoni, P. barberinus, S. sordidus, S. schlegeii, S. psittacus, and S. punctatus. n L. atkinsoni, and S. punctatus, period two fish were found to be larger than period one fish. For A. nigricauda, fish from Saipan were larger than fish from Tinian, and period one fish larger than period two fish, while no difference between time periods for Saipan was found for S. ghobban. Results suggested that the mean size of a reef fish species will increase with the distance from centers of population, and significant results were found to exist across families. This conclusion seems intuitively correct, although exceptions did exist. Fishing pressure, not only from spearfishing but other nearshore methods such as surround net, gill net, and hook and line, will also be greater near larger population centers such as Saipan. These other methods would also impact reef fish species, further supporting the findings of the analysis. 45

54 An interesting finding was that for three of the five species of Scarids for which significant differences in length by location were found, this significance was attributable to the difference between terminal phase males. This finding, although not entirely supported, makes sense in the consideration of spearfishing, especially at night. The brilliantly colored terminal phase males are larger and easier to observe while spearfishing. t would be expected that these fish would be taken preferentially. n areas of heavy fishing or for species that are heavily fished, terminal phase males would be over-exploited, resulting in a decrease in number of older cohort fish. Both S. sordidus and S. psittacus are small species which inhabit reef flats, lagoon and seaward reefs to depths of at least 5 meters (Myers 1991), readily accessible habitat for spearfishers, but also areas where other methods such as surround and gill nets are intensively used. Time period was not found to have had a significant effect on mean fish length, as no consistent trend emerged from the analysis. This would be expected for the time periods used in this analysis since fishing pressure around both Saipan and Tinian has probably been consistent over a number of years. This indirectly supports the above results that length is dependent upon location. t would be expected that if fishing pressure were consistent from year to year that species in general would be smaller in Saipan than in Tinian due to the proximity of reef resources to a larger number of fishers. t may also be expected that given a constant effort, fish would get smaller from year to year, until reaching a minimum size. This hypotheses is partially supported by the significant differences found in terminal phase males of some Scarid species. Conclusion Differences in CPUE between the time periods analyzed were significant and raise concern. The fishing methods employed were similar, and some differences in the documentation of information have been addressed. Collection and use of the variables in DFW 94- in the adjustment of CPUE raises very important issues with regard to the 'how' of generating meaningful values. How many and what type of variables to include are important questions that need to be addressed. The variables that will have the largest affect on CPUE are probably those associated with oceanographic conditions and market forces. These variables must be easily obtainable and shown to have exerted some affect on CPUE in a preliminary study, prior to their being used in the adjustment ofcpue values for long term monitoring. The analysis of length data showed significant differences in length related to location. The family Scaridae in particular appeared to show distinct differences in length by location, with length being smallest around Saipan for most species. These results can be interpreted to infer partial support for the lower percent composition of Scarids landed in the Southern slands. Also, the lower percentage of terminal phase males in the Southern slands, in particular Saipan, partially support findings where significant differences in length could be attributed to the smaller size of terminal phase males. t can be argued that these results are highly skewed by the fact that data were collected from different fishing companies targeting different species, or differently sized fish of the same species or family group. Although such an argument is certainly valid, it is difficult to dismiss the fact that the more fish that are landed by weight, the more money the company and fisher will make. Targeting larger fish would be more efficient than chasing smaller ones, although it 46

55 could also be argued that larger fish in the Northern slands are more susceptible to fishers than counterparts in the Southern slands due to the remote location, hence insignificant fishing pressure of those islands. The results from analysis ofcpue, length frequency, and species composition combined attest that reef fish stocks in the Southern slands are significantly exploited, and that some families, such as the Scaridae in particular, may be near a critical exploitation rate. n any fisheries monitoring program the collection of a number of parameters is required, and such collection must be in a consistent and continuous manner. The data sets analyzed fall short of such requirements, although the results are nonetheless conspicuous. To fully determine the status of reef fish stocks in the Southern Mariana slands, a comprehensive approach, as detailed in DFW 94-, is necessary. Monitoring the long term condition of a complex multi-species ecosystem such as that of a coral reef requires considerable planning, manpower, monetary funding and logistical support over a decadal scale. The opportunity to institute such a program exists for the CNM, and should therefore be pursued. A) Reef Fish Market Sampling. Recommendations 1) Standardization of CPUE. The variables that affect CPUE need to be identified, and collected over the long-term. These variables are probably primarily environmental and economic in nature. Standardization is required to conclude with confidence that significant changes have occurred. ) Species Composition. Collection of species composition data over time provides information on community structure, and its resiliency. Changes in species composition can serve as indications of over-exploitation or provide insight into the influence of environmental conditions. 3) Length Frequency. As demonstrated in the above analysis, significant changes in length can serve to support other parameter results. n addition, many length-based methods are available that can be used to estimate parameters such as growth and mortality, which are used in determining stock status. 4) Size at Maturity. The determination ofthe size at which a species attains sexual maturity and hence reproductive activity is perhaps one of the most important parameters in fisheries science. Extensive literature searches should be conducted to acquire all available information for species that occur in CNM, followed by studies to determine these sizes for select species. 47

56 B) Surveys and Experiments. n addition to reef fish market sampling, periodic underwater surveys should be conducted in fishing zones to independently monitor the population status of both commercial and non-commercial reef fish species. These surveys would provide a concurrent approach to determination of species composition and potentially length frequency. Depletion experiments in areas of low fishing pressure and areas of varying fishing pressure would be useful in obtaining estimates of species densities, and subsequently estimating populations from different areas and/or islands C) Regulations All of the above recommendations are based on the present reef fisheries. The species specific size regulations in existence are not considered to be effective in managing reef fisheries. t is difficult to confidently estimate the size of a fish when using SCUBA-spear at night, and it is not possible to select the size of a fish when using a surround net or hook and line. Once a fish is landed at dockside it is usually dead and determination that it is undersized is ineffectual. n addition, the manpower required to effectively sample and measure a significant portion of the total reef fish landed in any given time period would be arduous and costly. The issue of size regulations was addressed in DFW 94- and many minimum sizes were found to be in error. t is believed that the minimum size requirements not be utilized for the management of reef fishes. Rather, it is believed that reef fisheries be managed by method, and that some of the methods currently in use, such as SCUBA or hookah and spear, be eliminated. t is also believed that indiscriminate methods such as gill-netting also be eliminated. The idea is to support the more traditional methods of fishing, in order to exact less fishing pressure on reef fish species. With certain exceptions such as talaya, monofilament nets should be eliminated due to their destructive nature on fisheries habitat. Whatever regulatory approach the CNM takes in the management of its reef resources, the regulations need to be practical, enforceable and effective. 48

57 REFERENCES Allen. G. R Synopsis of the circumtropical fish genus Lutjanus (Lutjanidae). n: Tropical Snappers and Groupers: Biology and Fisheries Management, pp Ed. by J. J. Polovina and S. Ralston. Ocean resources and marine policy series. Allen, G. R. and F. H. Talbot Review of the snappers ofthe genus Lutjanus (Pisces:Lutjanidae) from the ndo-pacific, with the description ofa new species. ndo Pacific Fishes No.ll, 88 pp. Amesbury, S.S Assessment offish communities in the Mariana Archipelago. n: Assessment ofnshore Marine Resources in the Mariana Archipelago, pp 7-49, Sea Grant Project No. UG/R-4. Amesbury, S.S. and R.F. Myers Guide to the Coastal Resources of Guam. Volume, The Fishes. University of Guam Marine Laboratory, Contribution No p. Anderson, W. D Systematics of the fishes of the family Lutjanidae (Perciformes: Percoidei), the snappers. n: Tropical Snappers and Groupers: Biology and Fisheries Management, pp Ed. by J. J. Polovina and S. Ralston. Ocean resources and marine policy series. Dowdy, S. and S. Wearden Statistics for research. John Wiley & Sons, Second Edition. 69 pp. DFW Five-year progress report fiscal years DFW Technical Report Biological analysis of the nearshore reef fish fishery ofsaipan and Tinian, Commonwealth ofthe Northern Mariana slands, Division offish and Wildlife, 14 pp. DFW Technical Report Checklist of Fishes of the Commonwealth of the Northern Mariana slands. Commonwealth of the Northern Mariana slands, Division of Fish and Wildlife, 5 pp. DFW Biological analysis of the nearshore reef fish fishery; data collection, storage, and processing. Commonwealth of the Northern Mariana slands, Division offish and Wildlife, 13 pp. DFW Biological analysis of the nearshore reef fish fishery; data collection, storage, and processing. Commonwealth ofthe Northern Mariana slands, Division offish and Wildlife, 14 pp. FY94 Annual Report (1995). Sportfish Restoration Act Research Program, Commonwealth of the Northern Mariana slands, Division offish and Wildlife. FY95 Annual Report (1996). Sportfish Restoration Act Research Program, Commonwealth of the Northern Mariana slands, Division offish and Wildlife. 49

58 the Northern Mariana slands, Division of Fish and Wildlife. Hicks, C.R Fundamental concepts in the design of experiments. Saunders College Publishing. Third edition 377 pp. Masuda, H., Amaoka, K., Araga, c.,uyeno, T. and T. Yoshino The fishes of the Japanese Archipelago. Tokai University Press, Tokyo, Japan. 437 pp. Myers, R. F Micronesian reef fishes: A practical guide to the identification of the inshore marine fishes of the tropical central and western pacific. Coral Graphics. 3 pp. Potvin, C., and D. A. Roff Distribution-free and robust statistical methods: Vialbe alternatives to parametric statistics? Ecology 74(6): Randall J. E A preliminary Synopsis of the groupers (Perciformes: Serranidae: Epinephelinae) of the ndo-pacific Region. n: Tropical Snappers and Groupers: Biology and Fisheries Management, pp Ed. by J. J. Polovina and S. Ralston. Ocean resources and marine policy series. Randall, J. E., Allen G. R., and R. C. Steere Fishes of the Great Barrier Reef and Coral Sea. University of Hawaii Press, Honolulu, H. 57 pp. Sainsbury, K. J., Kalida, P. J., and G. G. Leyland Continental shelf fishes of North and Northwest Australia. Fisheries nformation Service, Canberra, Australia. XX pp Shapiro, D. Y Reproduction in Groupers. n: Tropical Snappers and Groupers: Biology and Fisheries Management, pp 95-38, by J. J. Polovina and S. Ralston. Ocean resources and marine policy series. Smith, M. M. and P. C. Heemstra Smith's Sea Fishes. Springer-Velag. 147 pp. Shaw, RG. and T. Mitchell-Olds ANOVA for unbalanced data: an overview. Ecology 74(6): Thresher, R. E Reproduction in Reef Fishes. T.F.H. Publications, nc. Ltd. 399 pp. 5

59 APPENDX A 51

60 '" Frequency tv tv tv co ',, ' 16to 17 iii i i!!! 18 to 19 '" to 3 3 to 4 4 to 5 5 to 6 Frequency '-" v. '" '" V> 6 to 7 t1 V... tv L 7 to 8... ;:. ;::... li:: to 3 ;::.. 8 to 9 ;:.. i:! i:! t'""" c:l-.. (> ;:l 9 to 3 S' c:l- OQ t'""" g. (> S' ::r :::: ;:l 4 to 5... OQ ;::.. """"', n 3 to 31 ::r :::: """"' n 31 to 3 6 to 7 ;::.. ;;: "' 3 to 33 "' ;;: S" ;:: S" 33 to 34 a- 8 to 9 ;:: ;:l a- li 34 to 35 -l tv 3 to to 36 ;:l 36 to _ -Vl 37 to 38

61 5 r Acanthurus lineatus - Northern slands _. '" c- o «1... on r- oo B B B '" B '" B '" B '" B '" B '" B '" B '" B '" B '" B '" B r- oo ::=:... on r- oo N N N N N N N N N "" '" '" '" Length (cm) '" '" '" '" Acanthurus lineatus - Southern slands n = _._...- ::l r r r-.- r _._.- 4 r- :- -.- t _._._.._.._.!-.- r-.- r L.J.1 _ LL.J... l.j...j... l.j...j... l.j.. 1 ::=:... N... Vl... eo a. N N '" '" '" N «1 B B B B B B B B S B B B '" B '" B '" B B ;:'!: Vl r- eo - ::=: N '" '" '" '" '" '" '" '" Length (cm) 53

62 16 to to to 19 Frequency Frequency to..,. C\ to..,. C\ tv..,. C\ to 3 3 to 4 '!! ' i to 19 to 4 to 5 V1 S to 1 ::to Ei' 5 to 6 1 to ;:::. '" "" i" r "" r 6 to 7 '". ('> ('> to 3 cs. '" cs. '" ::l ::l!:;. (') (') 3 to 4 3 '" 7 to 8 '-' S. 4 to 5!\ ;::... ;:::. 8 to 9 ::;. "".., ;: 5 to 6 ;: S- 6 to 7 9 to 3 u. 7 to 8 8 to 9 3 to 31 9 to 3 31 to 3

63 Gnathodentex aurolineatus - Northern slands 18 n= ;>.. u C) ;:J cr C)... ( '" ;:::; N «) N N N '" N - N N N Length (cm) 1 Gnathodentex aurolineatus - Southern slands 1 8 C) ;:J ' C)... ( '" N () N M N N N B B 8 8 B V) ;:::; N N Length (cm) 55

64 Lutjanus kasmira - Northern slands u 4) '" ;::s 5 "' 4)... "'"' N M N N N N N N N Length(cm) Lutjanus kasmira - Southern slands :!: N -N N N B B B B B B B B N "" :!: N N N N '"" Length(cm) 56

65 Myripristis berndti - Northern slands >-. 4 u!=: Cl) ;::s '..,.. 3 \ t- a. ;:::; N,.,..;-... N N N N!: ;:::;,., N N N Length(cm) Myripristis berndti - Southern slands 8 r >-. u!=: Cl) ;::s ' Cl)....., ,.,..;- :! t: N N... :!!:...,.,... - N N... Length(cm) N 57

66 16to 17. c '... Frequency V a _. V. '\ o o o o a o a o ' " iii i... Frequency N tv w w a a '. V r i '" :> r i: (> ::l '" (1Q So,.-... ;:: ("')... :::- '" ;:: i} :> ;:: a., So "' " i} 6 to 7 7W8 8 to 9 9 to 3 \.j>. w 7 to 8 8 to 9

67 Parupeneus bifasciatus - Northern slands :>-. u a:: \) " \) r- oo '"... N '"....,., \ r- oo N N N N N N N N N N B B B B B B B B B B B E 8 8 \ r- oo N N... r- oo N N N N N N N N N '" '" '" "" '" '" '" Length (cm) Parupeneus bifasciatus - Southern slands 45 4._ _..-.._-----_. n=6 35 f- 1- i f- f- f-._ _... _ :>-. u 5 a:: f- f- f- f _._ \) g. \) f- f- f-... f _..._._ _ l- t f- f-,- f- - -,- f- _.-_._._._----_... _- 5 f- f- f- i_ - i_ f- i- f- - f LL l..l LL l..l LL l..l LL l..l l..l l.j.. u N '" N... \ r- oo N N '" N N '" N N N N N '"....,., N N '"... N N N N '" N '" "" B B B B B B B B B B B B B B B B '" r- oo a- N N N Length (cm) 59

68 Pterocaesio tile - Northern slands ;>-. u C <l.l ;:J ry <l.l '" N N N N "" '" '" Lcngth(cm) N Pterocaesio tile - Southern slands 5 r _... _._... _._ N V) N N N N '" B B '" B '" ;::; N N N <" N '" N '" Length(cm) 6

69 Frequency Frequency V... ".. o '" '" " f"'lj,..,.,,,.,.,,,..,.,,,,,,!,,, "'T,,"'" '""!,.,.,.,..",.,.,,!"'T, "'" '""!,.,., 'T"'.,.,.,..,,1""', """"""!'' o V w.,j:o. V \ -..J c:::::::::::j " '" " ' -"1 r ::l r 8 to 9 f=!!! 1:1.. i! 1:1.. i! r ::l... CJQ,... ;:: 3 So '-' "' e-, 9 to 3 3 to to 3 3 to So "' ::;- i:i" := ::;- i:i" := 3 to to to to to to to 36

70 Frequency Frequency '1 tv os. 15 to 1 17 to 1 19 to 1 to 3 t 5 t 7 t 9 to 3 31 to 3 33 to to to to 4 41 to 4 43 to to to to 5 o '"... a- " ", = '" o,,,,!... ::s tv tv - i :l i:! i:! '" to to 4 to 6 to 8 to 3 to 3 3 to 3 c::.- 34 to 3 l' (' :':. c::, ::s S' o.s. ::r 36 to 3,--, (') :: 38 to 39 '" - 4 to 4 48 to 49 5 to 51 5 to to 55 o '"... a- o '" : ', ",,!- ;. ;:. - 1 == 1! -!! ---.J!.j:o.! ' 1! i --' :; - 9 :::- 4 to 43 ::;.. 44 to 45 -:l ;:: 46 to 47 i:! '" c::.-. if So ;:: ::;.. S'