CI1Y ISLAND HABITAT RESTORATION FISH AND INVERTEBRATE MONITORING. Final Project Report. City of Sarasota P.O. Box 1058 Sarasota, FL 34230

Transcription

1 CI1Y ISLAND HABITAT RESTORATION FISH AND INVERTEBRATE MONITORING Final Project Report Prepared for: City of Sarasota P.O. Box 1058 Sarasota, FL Prepared by: Mote Marine Laboratory 1600 Thompson Parkway Sarasota, FL Randy E. Edwards, Ph.D. Principal Investigator November 13, 1992 Mote Marine Laboratory Technical Report Number 277. MOTE MARINE LABORATORY LIBRARY 1600 THOMPSON PARKWAY SARASOTA, FLORIDA ~ p r:;j~jr;:i\djt?rl~,i I.;1.lJJ'.~. J... '\ \ \ \ f : \ NOV : ---_... _...--_

2 TABLE OF CONTENTS LIST OF FIGURES ii TABLES IV EXECUTNE SUMMARY V INTRODUCTION... 1 ME11IODS Study Site Sampling Techniques... 2 Monitoring Schedule... 2 RESULTS AND DISCUSSION CONCLUSIONS Sampling Techniques... 5 Differences Between Ponds... 5 Relevance to Design of Future Projects (Including Modification of the City Island Project Subjective Evaluation of Fishery Productivity Estimates of Total Abundance of Snook, Red Drum, and Striped Mullet... 7 Project Valuation Estimations with Regard to Valuable Fishes LITERATURE CITED... 10

3 LIST OF FIGURES Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Study site. Number of fish (all species) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event-18). Number of juvenile snook (Centro porn us undecimalis) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event-18). Number of juvenile red drum (Sciaenops ocel/atus) collected at each station (pond) during each sampling event during the monitoring period 8/1191 (Event-I) to 4/2/92 (Event-18). Number of juvenile striped mullet (Mugil cephalus) collected at each station (pond) during each sampling event during the monitoring period 8/1191 (Event-I) to 4/2/92 (Event-18). N urn ber of spot (Leiostornus xanthurus) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event- 18). Number of pinfish (Lagodon rhornboides) collected at each station (pond) during each sampling event during the monitoring period 8/1191 (Event-I) to 412/92 (Event- 18). Number of siversides (Menidia sp.) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event- 18). Number of gulf killifish (Fundulus grandis) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event- 18). Number of mojarra (Eucinostornus sp.) collected at each station (pond) during each sampling event during the monitoring period (Event-I) to 4/2/92 (Event- 18). Number of bay anchovy (Anchoa rnitchilli) collected at each station (pond) during each sam piing event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event- 18). Number of menhaden (Brevoortia sp.) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event- 18). Number of sheepshead minnow (Cyprinodon variegatus) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-I) to 4/2/92 (Event-18). ii

4 Figure 14. Figure 15. Number of longnose killifish (Fundulus similis) collected at each station (pond) during each sampling event during tbe monitoring period 8/1/91 (Event-1) to 412/92 (Event-18). Distribution of marsh fishes, planktivorous fishes, mojarras, commercial and recreational fishes, and spot + pin fish in the total catch from the City Island ponds. Figure 16. Figure 17. Distribution of all snook and red drum collected from the ponds. Predicted high tide levels for Sarasota Bay during early III

5 TABLES Table 1. Table 2. Complete fish abundance data set. Comparison between numbers of fishes collected on higher-high and lower-high tide sampling events. iv

6 EXECUTIVE SUMMARY (1) In order to assess the some of the impact and value of a habitat restoration project (1.8 ha of restored intertidal wetlands and newly created saltwater ponds) on City Island (City of Sarasota, FL), flshes and large invertebrates were monitored (by seining flve ponds) 18 times (bi-monthly) over the period from January 1991 to April (2) Fish were abundant in the City Island ponds, and 6,262 individuals of23 species (or genera) were collected during the monitoring period. (3) Macro-invertebrates were not abundant, and only 58 individuals of eight species (or genera) were collected during the monitoring period. (4) With the exception of marsh fishes and silversides that inhabit shallow environments throughout their life cycle, the fishes were juvenile stages of species that are normally found in deeper environments of the bay as adults. (5) Fishes valuable in local commercial and recreational fisheries that were collected from the pond included striped (black) mullet, red drum, snook, black drum, and permit. (6) All of the five ponds were very different with respect to tbe types offish that utilized them. (7) The three sballowest ponds (ponds 3,4, and 5) were dominated by marsh fishes, like killifishes, sheep shead minnows, and sailfln mollies. (8) The deepest pond (pond 1) was dominated by planktivorous fishes (menhaden, silversides and anchovy), although mojarras, marsh fishes, and juvenile spot and pinfish were also abundant. (9) The second-deepest pond (pond-2) bad a fish community that was similar to that of pond 1, except that mojarras were more abundant that planktivores. (10) Juvenile snook were collected only from pond 1 (71 %) and pond 2 (29%). (11) Juvenile red drum were collected only from pond 2 (32%), pond 3 (32%) and pond 4 (36%). (12) Because of normal seasonal cbanges in tidal regime, ponds 1 and 2 were almost totally isolated from the other ponds and from the bay during late winter and early spring. (13) The distribution and abundance of red drum and otberwinter-spawning flshes probably was limited by the tidal isolation of ponds 1 and 2. (14) Over twice as many fish were collected in sampling events timed to coincide with the lowesthigh tide of the lunar month, as compared with sampling timed to coincide with the highesthigh tides, indicating that sampling on high tides (as specified by FDER) is not advisable. (15) Based on SUbjective comparison with previous field studies in natural environments, pond 1 and pond 2 were judged to be above average with regard to overall fish abundance, while ponds 3, 4 and 5 were judged to be average or slightly below average. v

7 (16) With regard to red drum, ponds I, 2, and 3 were judged to be above average relative to abundances typically found in natural environments, but the ponds do not approach the order-of-magnitude greater abundance found in highly productive natural habitats. (17) Similarly, with regard to snook, ponds 1 and 2 are above average relative to natural habital~, but do not approach the productivity of some natural habitats that can be ten times or more as great. (18) Pond 5 shows some indication of being valuable as a first nursery habitat for some fishes, particularly striped mullet. (19) Minor modifications in design ( primarily with regard to depth, shape and structural complexity) could be incorporated into the City Island project and future projects at relatively low cost. (20) The potential return of the suggested modifications could far exceed their costs (in terms of economic costlbenefit analyses). (21) Because of their low cost and potential for high return, such modifications should be tested by modification of the City Island project and inclusion into new habitat restoration projects. VI

8 IN1RODUCTION The Sarasota Bay National Estuary Program (NEP) has identified habitat loss as one of the major problems in Sarasota Bay. Recently, habitat losses including 78% of natural shorelines (Roat and Alderson, 1990), 35% of seagrass area (Duke and Kruczynski, 1992) and 42% of wetlands (Estevez, 1992) have been documented for the bay. Loss of intertidal and shallow subtidal habitats is particularly critical relative to Sarasota Bay fisheries because of the value of these environments as essential nurseries for recreationally and commercially valuable fish and invertebrates (Edwards, 1989), and because the amount of these types of environments in the Sarasota Bay system is relatively small (Edwards, 1992). In view of this situation, habitat restoration and enhancement actions have received high priority in the Sarasota Bay NEP. However, the amount of Sarasota Bay shoreline that can be available for habitat creation, restoration or enhancement is very limited and is restricted to that which is publicly owned, that which can be publicly acquired at a reasonable cost, or that which private owners are willing to provide. Overall, only a small portion of the present bay shoreline falls into these categories. Therefore, if habitat restoration is to make a significant contribution to Sarasota Bay, each project must be highly productive -- as close to optimaliy productive as is reasonably possible. Unfortunately, techniques for creating optimaliy productive habitat have yet to be determined, although some progress has been made (Lewis, 1992). In this light, an experimental habitat restoration was proposed by Mote Marine Laboratory as a Priority Action Plan Demonstration Project and was approved by the U.S. Environmental Protection Agency in early The concept was to create habitat that was ecologicaliy complex and highly integrated in the hopes that such habitat would be highly productive with regard to valuable fisheries species. The project was initiated in November, Enhanced funding for the project was provided by the Florida Department of Environmental Regulation. The City of Sarasota provided in-kind services and project oversight, and the Florida Department of Natural Resources provided plants and staff for planting activities. Project construction and initial revegetation was completed in December As discussed above, one of the most important aspects of habitat restoration/creation efforts like the City Island (CI) project is the potential contribution to Sarasota Bay fisheries through production of fish and other organisms. Therefore, the project included a monitoring component which was designed to assess the productivity of the City Island Habitat Restoration with regard to fish and important invertebrates; and, at the same time, to obtain information about how future habilat restoration projects can be designed to increase their value in terms of fishery productivity. 1

9 METHODS Study Site The study site is a 1.8 ha area adjacent to the Sarasota Bay NEP office on City Island. The restoration consisted of creation of a series of five interconnected saltwater ponds and associated planting of a diverse community of wetland and ecotonal upland vegetation (Figure 1). The vegetation is currently being monitored under a separate contract to Mote Marine Laboratory. The system of ponds is connected to Sarasota Bay through one main outlet, although an additional connection occurs during extremely high tides. Each of the ponds is very different from the olhers in terms of bathymetry and circulation. Largely as a result of these differences, the intertidal vegetation patterns of the ponds are also different. Sampling Techniques As per specifications provided by FDER, sampling stations were established at each of the ponds (1-5, Figure 1). Each station was designed such that approximately the same area of water would be sampled at each of the pond stations. A seine (1.8 m in depth, 9.1 m in length with a 1.8 m x 1.8 m bag) constructed of 0.6 mm (bar) woven (Ace) nylon netting was deployed in a '1 shaped pattern along one shore of the pond. The end (top of the '1') was brought to shore, and the two ends of the seine were brought to about 2 m apart before the seine was hauled to shore. During hauling, care was take to insure that the lead lines maintained contact with the pond bottom at all times. When the bag reached the shore, the lead line and float line of the bag were lifted to trap fish inside the bag. Fish and macroinvertebrates collected in the seine were identified, counted, measured, and released back into the pond from which they were collected. Each organism was identified to species, except for those that could not be quickly identified in the field and could only be identified to genus. A few individuals of each species or genus were retained and preserved as reference specimens that would allow any questionable field identifications be validated. In some cases where more than 50 individuals of a species were collected at a time, total number was estimated to the nearest 25 individuals. Similarly, only a subsample of fish was measured when large numbers of a species were collected, and at least ten individuals (including the smallest and. largest) were measured (nearest millimeter -- standard length for fishes and carapace width for crustaceans). Estimation and subsampling was necessary to allow the fish to be released with minimum mortality, so that the monitoring would not greatly impact the fish populations. Mortality usually only occurred in the case of fish that became entangled or gilled in the net. Data for each pond was immediately entered on a separate field form. Monitoring Schedule The contract called for 18 monitoring events to be conducted on a roughly twice per month basis relative to tidal conditions. FDER specified that the ponds were to be sampled at high tide during periods of the highest high tides and lowest high tides of each lunar month, and provided a schedule of dates and times for sampling events. Monitoring commenced in 1anuary, 1991 and ended in April,

10 RESULTS AND DISCUSSION A total of 6,282 fish comprising 23 species or taxa (genera in cases where field identification to species was not feasible) were collected during the monitoring (Table 1). The total number of individual fish collected from the respective ponds during the 18 sampling events ranged from 956 (pond 1) to 1,753 (pond 2). However, due to differences in the degree to which the various ponds could be sampled effectively (e.g., due to size, depth, vegetation, obstructions, etc.) the differences in total numbers probably are not meaningful. Sheepshead killifish (Cyprinodon variegatus) was the most abundant species, accounting for 1,795 (29%) of the fish collected at all stations and all events. Mojarras (Eucinostomus sp.) (993, 16%), silversides (Menidia sp.) (628, 10%), longnose killifish (Fundulus similis) (513, 8%), sail fin mollie (Poecilia latipinna) (511, 8%), spot (Leiostomus XIlnthurus) (449, 7%), Gulf killifish (Fundulus grandis) (445, 7%) were also numerically important. Together, the above species accounted for 85% of all fish collected. Five species of local commercial or recreational value were collected: striped mullet (Mugil cephalus individuals), red drum (Sciaenops ocellatus - 22), snook (Centropomus undecimalis --14), black drum (pogonias cromis -- 10), and permit (Trachinotus falcatus -- 1). All specimens of Brevoortia in the reference collection were identified as gulf menhaden (B. patronus) and all Menida were identified as tidewater silversides (M peninsulae ). Macro-invertebrates were not abundant during the monitoring period, and only a total of 58 individuals were collected and counted. Invertebrates included: Melongena corona (crown conch -- 2 individuals), Melampus coffeus (9), Callinectes sapidus (blue crab --10), Callinectes sp. (24), Limulus polyphemus (horseshoe crab -- observed, but not collected),,palaemonetes sp. (8), Penaeus sp. (5), Uca sp. (primarily supra-tidal and not counted). Complete data (fish and invertebrates) for each monitoring event are provided as an appendix. Figure 2 shows the total catch from each pond at each sampling event during the monitoring period. Catches were low during sampling events (early December through mid February) and increased substantially thereafter. Several species showed distinct seasonal patterns of abundance. Snook (Figure 3) first appeared in the samples in November. Since the snook were about 50 mm long, they either had been in the pond for a month or more and were missed in prior collections, or they had moved into the ponds after they had metamorphosed into juveniles (which usually occurs at around 25 mm SL or less [Edwards and Henderson, 1987, McMichael et ll ]). One early-juvenile red drum (31 mm SL) was collected in mid December, but the rest were collected after January (Figure 4). This corresponds well with red drum spawning and recruitment patterns found in Tampa Bay (peters and McMichael, 1987) and the Manatee River estuary (Edwards, 1991). Juvenile black drum were collected early (August - December) in the monitoring period; their sizes ( mm SL) indicate that they were young of the year that entered the ponds sometime after their late winter-early spring spawning period (Murphy and Taylor, 1989). Juvenile striped mullet (Figure 5), spot (Figure 6) and pinfish (Figure 7), also winter-spawning species, began to be collected as small early juveniles after mid January. Several other species including silversides (Figure 8), gulf killifish (Figure 9), and mojarra (Figure 10) appeared to demonstrate bimodal patterns with peak abundances occurring in the fall, followed by low abundances during winter and increasing abundance in late winter/early spring. Gravid adult silversides were collected in November, indicating that this species can complete it's life cycle in the ponds. Bay anchovies (Figure 11) were present after late September, but their abundance was highest after November. Juvenile menhaden (Figure 12) were most abundant in the early fall; after which time they were present, but not in large numbers. Adult menhaden were not collected. 3

11 Sheepshead minnow (Figure 13) and longnose killifish (Figure 14) did not show distinct seasonal patterns of abundance, probably because these species are permanent residents with protracted spavming periods. Distinct differences in fish community structure in the ponds were apparent. In order to facili l~t e analysis, the fish community was divided into five groups: 1) marsh fishes -- fishes that typically arefound only in or near marshes and other intertidal habitat (Fundulus grandis,f. similis, F. confluentus, Cyprinodon variegatus, and Poecilia latipinna); 2) planhctivores -- fishes that feed primarily on zooplankton and phytoplankton, although detritus may be trophically important as well (Anchoa mitchilli, Brevoortia sp., and Menidia sp.); 3) mojarras -- benthic fishes of the genera Eucinostomus and GelTes), 4) spot and pinfish (Leiostomus xanthunt.s and Lagodon rhomboides), and 5) commercial and recreational species -- fish that are of direct value in local commercial and recreational fisheries (Mugil cephalus, Centropomus undecimalis, Sciaenops ocellatus, Pogonias cromis, and Trachinotus falcatus). Using these categories, the total catch from each of the ponds (plus all ponds combined) is depicted in Figure 15. Pond 1 was dominated by planktivores; although marsh fishes, mojarras, and spot + pinfish were also abundant. Pond 2 had a similar distribution, except that mojarras dominated and planktivores were second. Ponds 3, 4, and 5 were dominated by marsh fishes, which accounted for 71, 72 and 95% of the respective totals for each pond. The spot + pinfish category, which accounted for 14% of the fishes in pond 3 and 14% in pond 4, was the only other large category for ponds 3-5. Commercially and recreationally valued fishes were collected from all of the ponds (Figure 15). However, most (81 %) of the commercial/recreational species depicted in Figure 15 were striped mullet. Most of the rest of the valued fishes were snook or red drum, which together accounted for 77% of valued fishes other than striped mullet. The distribution of these two species is shown in Figure 16. Snook were collected only from pond 1 (71 %) and pond 2 (29%). Snook were not present in ponds 3, 4, and 5. Red drum were collected from pond 2 (32%), pond 3 (32%) and pond 4 (36%). Red drum were not collected from pond 1 or from pond 5. However, all except one of the red drum were collected during a period in which little or no connection or tidal exchange into ponds 1 and 2 existed (see below). Therefore, the red drum results may reflect the ponds' accessibilities to early-juvenile red drum more than the ponds' suitabilities as red drum nursery habitat. 4

12 CONCLUSIONS Samplin~ Techniques FDER specified that the ponds were to be sampled at high tide, with pairs of monthly sampling events scheduled to conform to periods of the highest high tides and lowest low tides each of lunar month. Reasoning for this specification was based on FDER's observations that, in other restoration projects, more fish were collected on high tide. This reasoning may be correct for fringing marshes created along open shorelines. In such cases, fishes may be found in greater numbers (within or immediately adjacent to the marshes) on high tides, whereas they retreat to other (subtidal) habitats during low tides. However, the situation at the City Island restoration site was very different. The ponds had very limited connection with the bay, and very few fish could enter or leave the ponds. It has been the P.L's experience that such enclosed areas are sampled much more effectively at low tide, when the fish are concentrated and do not have access to marsh vegetation for escape. It was for these reasons that MML originally proposed to sample the City Island ponds at low tide, on a monthly basis. This would have allowed the project to have been monitored for at least 18 months for the same cost. However, FDER insisted on the high-tide sampling schedule. The data from the monitoring shows that many more fish were collected on the lower high tides than the higher high tides. The total number of fish collected on lower-high tide events averaged 450, while the number on higher-high events averaged less than half as many (223). Using a non-parametric sign test (Snedecor and Cochran, 1969), eight pairs of lower and higher high tide data for event pairs 1-2, 4-5, 6-7,8-9, 10-11, 12-13, 14-15, and (Table 2) were used to test the null hypothesis that there was no difference between number of fish collected in the pairs. The null hypothesis could not be rejected at the p = 0.05 level. Therefore, although this.conservative test could not detect differences between numbers of fishes collected on higher and lower tides, it certainly contradicts the idea that more fish are collected on the highest high tide, and it indicates that it is not worth while to sample on higher high tides. The fact that so many more fish were collected on lower high tides supports the idea that sampling effectiveness increases with decreasing tide level. In the future sampling of confined environments like the City Island ponds should not be done at high tide. Differences Between Ponds The most obvious difference between the ponds is depth. Pond-l is generally deepest, followed in order by pond 2, pond 3, pond 4 and pond 5. Depth is probably most responsible for differences in fish faunas of the ponds. Differences in vegetation seem to be secondary, and in any event, are themselves influenced by bathymetry. Pond 5 was also affected by periodic storm water runoff that reduced salinity and imported fine-grained sediments, and these factors probably greatly influenced the fish fauna. The two deeper ponds (1 and 2) appeared to be deep enough for a planktonic food web to be developed and thus support planktivorous feeders. These two deep ponds had a generally more balanced and diverse fish community (Figure 15). On the other hand, ponds 3 an 4 may be too shallow to serve as habitat for many of the species that were abundant in ponds 1 and 2, and they were dominated by marsh fishes that are typical of shallow environments. 5

13 Relevance to Design of Future Projects (lncjudin~ Modification of the City Island Project) Overall design of the ponds does not maximize marsh/water interface, shoreline length etc. and does not maximize structural heterogeneity -- features that increase value and productivity of fish habitat (Weinstein, 1979; Edwards, 1991). Such features could be added to this or other restoration projects at very little additional cost, and could greatly increase the fishery habitat value of the projects. Although ponds 3 and 4 are productive in terms of marsh fishes, they could maintain that asset and additionally be productive of other types of fishes if some deeper areas were present (e.g., holes or fingers of deeper water). Conversely, ponds 1 and 2 might be more productive of marsh fishes if the shoreline were more irregular and included islands or peninsulas of marsh vegetation. Tidal exchange between the ponds and the bay is another important design feature. Exchange in the City Island system is limited by the small size and shallowness of the creek that connects pond 4 to the bay, and is further restricted by the connections between ponds. Although limited exchange may have positive aspects such as by restricting access of predators such as piscivorous fishes and large blue crabs, and of minimizing erosion and hydrologic scour, too little exchange can have serious negative impacts. Much if not almost all recruitment of young stages of commercially and recreation ally important species occurs at larvavpostlarval stages in which active migration is far less important than passive dispersal. Therefore, increased exchange could have could have resulted in increased recruitment, and therefore larger populations, of fish like snook, red drum, and black drum. Striped mullet, on the other hand, recruit to inshore nurseries at a migratory stage (Anderson, 1958) that does not depend totally on tidal dispersal. The small numbers of invertebrates collected during the monitoring may also be related to the limited exchange of the pond system and resultant low recruitment of larval stages. Not only was exchange limited, for some of the ponds it was non-existent for long periods. Water levels in ponds 1 and 2 were found to be very low during the early part of Observations and comparisons with predicted tidal levels in late March and early April led to the conclusion that the connection between ponds 2 and 3 was established only when the tidal level was around +2.3 ft above mean low water (0.0 ft). Predicted high tides for early 1992 are plotted in Figure 17 which shows that tides high enough to establish a connection between ponds 2 and 3 did not occur for a period of over two months. Therefore, with the exception of any stormdriven high tides during the period, ponds 1 and 2 were isolated and cut off from recruitment for this period. Not until almost the end of April were there any predicted tides that would exceed the 2.3 ft elevation by more than 0.1 ft. Additionally, Spartina planted along the connection between ponds 2 and 3 invaded the connection and restricted the water flow. Sedimentation may have increased as a combination of the Spartina growth and erosion during rain storms. As a result, pond 1 and pond 2 are isolated for long periods of time and receive substantial inflow only when tide levels are greater than about +2.5 ft. In the future, similar projects should take seasonal changes in sea level and high tide levels (Provost, 1973) into consideration. Modification of the connecting water bodies of the City Island project should be seriously considered, particularly since it is possible that sedimentation and marsh growth may continue to decrease water exchange. Subjective Evaluation of FisheD' Productivity The pond monitoring was not designed to provide completely quantitative estimates of the numbers of all fishes in each pond. As discussed above, this was not possible because of factors inherent in sampling natural systems and because of the limited funding available for the monitoring. In the rare cases where it is possible, extensive and costly efforts are required to 6

14 accurately quantify fish populations. Additionally, fully quantitative assessment would not have been possible in a situation in which a relatively isolated system is to be repeatedly monitored over time, because quantitative assessment would require that all the fishes be removed from each pond. Subjective evaluation of the fish populations is the best that is possible under the circumstances of the monitoring project. Therefore, the author used his experience in collecting fishes in other studies in the Sarasota Bay area (e.g., Edwards, 1991; Edwards, 1992) to classify the fish abundance and apparent productivity of each of the CI ponds according to the following numerical classification system: A = exceptionally high abundance/production, rarely found in natural systems; B = high production, uncommon; C = average abundance and production, common in natural systems; D = below average, common in natural systems; F = low production, common in natural systems. Applying this classification system to observed overall abundance and apparent productivity of fishes, the CI ponds would be subjectively graded as follows: pond 1 = B, pond 2 = B- to C+, pond 3 = C to D+, pond 4 = D, pond 5 = D. Additionally, pond 5 may have additional value in being above average (B- to C+) with regard to very small, newly-recruited juveniles. For example, EJ striped mullet (Figure 5) and EJ spot (Figure 6) utilized pond 5 when they first entered the site. These kinds of first nursery habitats are rare in nature, but are very important. For example, Kilby (1948) noted that small pools in marshes along the F10rida Gulf coast were primary (first) juvenile mullet habitat. The value of pond 5 might be enhanced if some excess stormwater could be diverted (e.g., through a system of ditches) to other parts of the system during unusually heavy rainfall events and if some of the sediment load from extreme events could be lessened. The fact that red drum and snook were regularly collected from some of the CI ponds, as compared to the average' situation in which no red drum or snook are collected in most seine samples of natural marsh shorelines (Edwards, 1991), indicates that the CI ponds are above average with regard to their value as habitat for these species. However, the numbers of snook and red drum collected do not indicate that the system approaches optimality for these species. For example, a similar net haul in exceptionally productive nursery habitats, thirty or forty juvenile red drum might be collected (e.g., Edwards, 1991) instead of three or four, as was the maximum in the City Island ponds. Similarly, instead of one or two juvenile snook (the most collected in any haul at CI), ten to twenty can be taken from extremely productive natural habitats (e.g., Edwards, 1991). Therefore, with regard to snook, pond 1 would be classified as high to above average (B to B ) and pond 2 would be classified as above average (B- to C+); since snook were not collected from the other ponds (3,4 and 5), they would be classified as average to below average (C to D) with regard to their value as snook nursery habitat. With regard to juvenile red drum, ponds 2,3 and 4 would all be classified as above average (B- to C+), while ponds 1 and 5 (no red drum) would be classified as average to below average (C to D). Estimates of Total Abundance of Snook, Red Drum. and Striped Mullet The monitoring design specified by FDER did not provide the opportunity to obtain quantitative estimates of the abundance or production of key species in each pond. Therefore, in order to estimate the abundance of juvenile snook in the ponds, a supplemental, thorough sampling was performed on 10/30/92. At this time of the year, most if not all of the juveniles from the 1992 summer spawning could be expected to have been already recruited and present in the ponds (McMichael et J!b 1989). Pond 1 and pond 2 were each sampled with four seine hauls that 7

15 covered the entire area of the pond. A total of 12 snook (9 early juveniles < 125 mm SL, and 3 juveniles> 125 mm SL) were collected from pond 1, and three EJ snook were collected from pond 3. Based on the P.L's experience and on recent assessment of seining efficiency in similar ponds (Allen, et 1, 1992), it can be roughly estimated that about half of all snook in ponds 1 and 2 were collected, and that the remainder evaded the seine. The other ponds (3-5) were sampled thoroughly and no snook were collected. Because ponds 3-5 are sm aller and can be sam pled more effectively, it is unlikely that any snook were missed in the sampling. Therefore, it can be roughly estimated that there were about 30 juvenile snook living in the ponds. Since similar complete sampling was not performed during the period (late winter) when juvenile red drum and striped mullet were using the ponds, total abundance of these species can only be estimated. During the monitoring period, 22 red drum, 196 striped mullet and 14 snook were captured. Based on the ratio of 14 snook captured to 30 total estimated in October, 1992, an approximate ratio of2 can be applied to the totals for red drum and striped mullet. In this way the total abundance of red drum can be estimated at 44 and total abundance of striped mullet at 392. Project Valuation Estimations with Reg:ard to Valuable Fishes Total cost of the City Island Project was over $200,000. Although it is very difficult and sometimes misleading to attempt to directly calculate values for natural resources (Bell, 1989), the following analyses can put part of the project's value into perspective. First, a cost-benefit breakeven point for an almost perpetual investment such as is the City Island Habitat Restoration Project, an annual return of benefits should be equal to the potential return on the investment. For example, if the $200,000 had been invested for a very long term, a return rate of 10% (selected for ease of calculations in this illustration) might be reasonable and would yield an annual return of $20,000. It is against this potential return that the project's annual benefits should be compared. The benefits of the restoration are numerous and difficult to directly value. For example, the project has sociological (education, public relations), esthetics, and ecological values. The many ecological values of the project would be almost impossible to directly quantify. However, in the case of commercially and recreationally valuable species produced as a result of the restoration, rough estimates can be obtained. Looking only at the three most important commercially and recreationally valuable species (snook, red drum and striped mullet), annual returns were calculated as follows: the numbers of each of these species produced annually in the restoration site (estimates developed in preceding section) are multiplied by estimated values for individuals of each species to obtain annual values, which are summed. The value of a snook, red drum or striped mullet is hard to estimate. However, FDER has developed a list offish values (Chapter F.AC, Fish Value Rule) for use in economic impact statements (ElS). The most recent FDER EIS values for these species are $67.20/snook, $33.60/red drum and $6.70/striped mullet. Although these values may seem exceedingly high, recent economic analyses (e.g., Bell, et 1, 1982) have demonstrated that the recreational economic value of species like red drum is several times the retail cost of a fish that is sold for food. Therefore, the above estimates can be used as upper limits to values. Additionally, use of these values is particularly meaningful in habitat restoration projects funded from FDER's Pollution Recovery Trust Fund (such as the City Island project), which in some cases may have used the above fish values in levying fines that are a source of the Pollution Recovery Trust Fund. 8

16 Using these values and estimated total number of each species in the City Island ponds results in an annual value (return) of $6, for the number of snook, red drum and striped mullet produced by the project. If more-wnservative values, $20.00/snook, $lo.00/red drum and $1.00/striped mullet were applied, annual return would be $1, Actual values may be even less. The above analysis does not purport to accurately calculate the value of the City Island Habitat Restoration Project, but it does provide some perspective. Based on the estimates, from 7% to 31% of the project's break-even return could be attained from production of three commercially and recreationally valued species. The lower estimate is probably more reasonable and itself is probably an over-estimate. Based on the author's rough estimate above that, with modification and fine tuning, the system's productivity of snook, red drum, and striped mullet might be increased by around an order of magnitude by modifications whose costs are a small fraction of the overall project cost, it is clear that it would be worthwhile to do what is necessary to attain such higher productivity in this and other habitat restoration projects. If ten times as many of these fishes were produced, the annual return from this production would account for most, if not all of the return necessary for the project investment to have a positive net economic impact. Therefore, modification and fine tuning of the City Island project should be seriously considered. Additionally, advantage should be take of every possible opportunity to apply, test and further develop techniques to increase fishery productivity of future habitat restoration projects. 9

17 LITERATURE CITED Allen, D.M., S.K Service and M.Y. Ogburn-Matthews Factors influencing the collection efficiency of estuarine fishes. Trans. Amer. Fish. Soc. 121 : Anderson, W.W Larval development, growth, and spawning of striped mullet (Mugil cephalus) along the south Atlantic coast of the United States. U.S. Fish Wildl. Servo Fish. Bull. 58: Bell, F.W Application of wetland valuation theory to Florida fisheries. Report No. 95, Florida Sea Grant College, Gainesville. Bell, F.W, P. Sorensen and V_R Leeworthy The economic impact and valuation of saltwater recreational fisheries in Florida. Report No. 47, Florida Sea Grant College, Gainesville. Comp, G.S. and W. Seaman Estuarine habitat and fishery resources of Florida, pp , in W. Seaman, Jr. (ed.), florida aquatic habitat and fishery resources. Fla. Chapt. of Am. Fish. Soc_ Duke, T. and W.L Kruczynski Report on the status and trends of emergent and submerged vegetated habitats of Gulf of Mexico coastal waters. U.S.A Environmental Protection Agency, Gulf of Mexico Program, Habitat Degradation Committee. Edwards, R.E. and B.D. Henderson Experimental mass culture of snook (Centropomus undecimalis) larvae and juveniles. Proc. Gulf and Caribbean Fisheries Institute 38: Edwards, R.E The importance of early-juvenile habitat to Florida fishery recruitment. p. 38 in G.S. Kleppel and W.S. Seaman, Jr. (eds.), Fishery recruitment in Florida waters. Florida Sea Grant Technical Paper No. 57. Edwards, RE Nursery habitats of important early-juvenile fishes in the Manatee River Estuary system of Tampa Bay. pp in S. Treat and P.A Clark (eds.), Proceedings, Tampa Bay Area Scientific Symposium 2. Edwards, R.E. 1992_ Fishery resource assessment. Sarasota Bay National Estuary Program Technical Project Report. Kilby, J.D A pd iminary report on the young striped mullet (Mugil cephalus Linneaus) in two Gulf coastal areas of Florida. Q. J. Fla. Acad. Sci. 11:7-23. Lewis, R.R, III Coastal habitat restoration as a fishery management tool. p in RH. Stroud (ed.), Coastal habitat restoration as a fishery management tool. McMichael, RH., Jr., KM. Peters and G.R. Parsons Early life history of the snook, Centropomus undecimalis, in Tampa Bay, Florida. Northeast Gulf Science 10:

18 Murphy, M.D. and R.G. Taylor Reproduction and growth of black drum, Pogonias cromis, in northeast F1orida. Northeast Gulf Science 10: Peters, KM. and R.H. McMichael, Jr Early life history of the red drum, Sciaenops ocellatus (Pisces Sciaenidae), in Tampa Bay, F1orida. Estuaries 10: Provost, M.W Mean high water mark and use of tidelands in F1orida. F1a. Scientist 36: Roat P. and M. Alderson State of the bay report. Sarasota Bay National Estuary Program. Snedecor, G.W. and W. G. Cochran Statistical methods, 6th edition. Iowa State Univ. Press, Ames. 593 p. Weinstein, M.P Shallow marsh habitats as primary nurseries for fishes and shellfish, Cape Fear River, North Carolina. Fish. BulL 77:(

19 Table 1. Complete fish abundance data Get. Sampling Event I f-+ 5-5~ Pond 1 I D 2 L ~r4t~_ FISHES Anchoa mitchllll 5 3 Brevoorlia sp Chloro8Combrus chrysurus Centropomu8 undecimalis Cyprinodon variegatus lapt9ru8 plumieri 1 Euclnostomus sp Fundu/us confluentus Fundulus grandis Fundulus slmllis Hippocampus sp. Lagodon rhomboides Leiostomus xanthurus Microgoblu8 gulosu8 Menidla 'p Mugi/ cephslus Mugil curema 10 Orthoprist/s chrysoplera PoeciIJa latipinna as Pogon/ss crom;s 3 3 Sc/aenops oce/latu8 Strongylur p. Trachinotus fa/catus TOTAL 35 ' B 17 13

20 Tabla 1. Complete fish abundance data set. Sampling Event ~ f-h _ Pond 1 2 I I 2 1 _ ~C~1 5 FISHES Anchoa mit chilli B Brevoortia sp Chloroscombrus chrysurus Centropomu8 undecimajis 2 Cyprlnodon variegatus B sa 3 3 B Diapterus plumieri Euclnostomus sp Fundulus confluentus Fundulus grandls Fundulus simllis B Hippocampus sp. Lagodon rhomboldes 2 3 Lelostomu8 xsnthurus 1 Mlcrogoblus gulosus Menldla sp sa 5 3 Mugil cephalus Mugil curema Orthopristis chrysopters Poecilia/atipinna PogonJas crom;s 1 Sciaenops oceliatus Strongylura sp. Trachinotus falcatus TOTAL sa

21 Table 1. Complete fish abundance data.et ---_.. -. Sampling Event Pond 213T4 :L5 ~ FISHES Ancho. milchilli Brevoortla sp Chloroscombrus chrysurus Centropomus undecimalls 2 Cyprinodon variegatu Di.pterus plumlerl Eucinostomus sp. ~ Fundulus conl/uontus Fundulus grandis Fundulus sl.tli1j& Hippocampus sp. Lagodon rhombolde. 7 8 Le/ostomus xbnthurus Microgoblus gujosus Menidlasp MugiJ cephalus Mugil curema Orthopristls chrysopter. P09cilla/atipinna Pogan/as cramis Sc/s9nops 000ll81u srrongylur p. Trachinotus fa/catus TOTAL

22 Table 1, Complete lish abundance data set TOTAL TOTAL TOTAL TOTAL TOTAj Pond I 1 I 2 I 3 I 4 I 5 I I I 2 I 3 I 4 I 5 I 1 I 2 I 3 I 4 I 5 II 1 I 2 I 3 I 4 I 5 TOTAL - -- FISHES Anchoa mitchjljj BrevoorUa sp Chloroscombrus chrysurus Centropomu8 undecimalls Cyprinodon variegatus Dlapleru8 plumlerl Euc/nos1omus sp Fundulus conf/uenlus Fundulus grandis Fundulus similis Hippocampus sp, Legadon rhombaides Leiostomus xanthurus Microgobius gu/asus Menidl. 'p MugU ceph.,us Mugil curame Orthoprist/s chrysopl9r PoeciJia latipinna Pogan/as cromls fo ScJsenops aeel/atus S/rongylur. sp Trachinotus (alcatus TOTA] TOTAL

23 Table 2. Comparison of numbers of fish collected on lower-high tide sampling events with numbers of fish collected on higher-high tide events. Lower-High Tide Higher High Tide Difference Event No. Event No. (Lower - Higher) *** Total 4251 Total Ave. 472 Ave *** Lower-high tide event missed.

24 0). tit)... ;f UJ > -.. ~ ~ Z 0 ~ ' ~ 9i.. 0 l'; Z 8 I J- LU ' t f 2N. '. i1!!' - -' )... ' ~ ~ :r ~ ~... ' < ~ x.. 8!!i1 > < m < I o U) < cr < U) :~.,: ~ :J.Ql LL

25 ALL FISH (All species combined) UJ (ij :::J 0 :~ 0 c '0 ~ ~ E :::J Z POND Sampling Event Figure 2. Number of fish (ali species) coliected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

26 SNOOK (Centropomus undecimalis)].!!2 al :::J -0 -;; '5.E '15.N E :::J Z Sampling Event POND 5 Figure 3_ Number of juvenile snook (Centropomus undecimalis) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

27 RED DRUM (Scianops ocellatus) ~ 3 ::s ] 'i ~ E ::s z POND Sampling Event POND 5 Figure 4. Number of juvenile red drum (Sciaenaps acel/atus) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

28 STRIPED MULLET (Mugil cephal us)..!!2 «I :::J :~..5 (5... ~ E :::J Z Sampling Event 18 Figure 5. Number of juvenile striped mullet (Mugi/ cepha/us) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

29 SILVERSIDES (Menidia sp.) en ttl :::J 0 :~ 0. (; E :::J Z POND Sampling Event Figure 8. Number of siversides (Menidia sp.) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-i) to 4/2/92 (Event-i8).

30 PINFISH (Lagodon rhomboides) ~ ~ U :~ -g a... ~ E ~ z. POND 1. POND 2. POND 3 POND Sampling Event Figure 7. Number of pinfish (Lagodon rhomboides) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-i) to 4/2/92 (Event-iS).

31 SILVERSIDES (Menidia sp.) en 1 «I 1 ::l 'U :~ 'U.E '0 ~ E ::l Z POND Sampling Event Figure 8. Number of siversides (Menidia sp.) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-i) to 4/2/92 (Event-18).

32 GULF KILLIFISH (Fundulus grandis) f/) ~ 0 :~ 0 E 15 ~ E ::l Z Sampling Event Figure 9. Number of gulf killifish (Fundulus grandis) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

33 MOJARRAS (Eucinostomas sp.) (ij ' ::> U.:> '6..s a ] E ::> z POND Sampling Event Figure 10. Number of mojarra (Eucinostomus sp.) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

34 BAY ANCHOVY (Anchoa mitchilli) en <ti ~ -u.;;: '0 c: '0 ] E ~ z )~7/// ~7 ~7~7/~~7~7 ~7'j~7 'j<j/<j~~n~ Sampling Event POND 5 POND 1 Figure 11. Number of bay anchovy (Anchoa mitchill1 collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

35 MENHADEN (Brevoortia sp.) ~ ::I :~.. (5... ~ E ::I Z Sampling Event. POND 1 POND 2 POND 3 POND 4 POND 5 Figure 12. Number of menhaden (Brevoortia sp.) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

36 SHEEPSHEAD MINNOW (Cyprinodon varigatus) 1 en <U ::::J -0 :~ ~ Q).0 E ::::J Z Sampling Event POND 3 POND 4 POND 5 Figure 13. Number of sheepshead minnow (Cyprinodon variegatus) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

37 LONGNOSE KILLIFISH (Fundulus similis) en lii ~ -0 :~ -0.s '0 ~ 1l E ~ z POND Sampling Event Figure 14. Number of longnose killifish (Fundulus similis) collected at each station (pond) during each sampling event during the monitoring period 8/1/91 (Event-1) to 4/2/92 (Event-18).

38 POND 1 POND 2 F_ (18.3%1 Spot & IinIish (1~6.2%1- ' I. Mao.h F_ (19.71 Comm./Pe:. So (D.3%) ~,I:., \ t.1oja< (:YJ.2%I~_C27. '1 POND3 POND 4 Spot lpjioh (I~l~ Mojarra$ (~!I-r ~~I~~/~WffiWffiW/~ POND 5 ALL PONDS Figure 15. Distribution of marsh fishes, planktivorous fishes, mojarras, commercial and recreational fishes, and spot + pinfish in the total catch from the City Island ponds. See text for further explanation of the categories.

39 SNOOK Pond 3,4 & 5 'U.trh Pond 2 '''0.('-.. ' (71.4%) Red Drum,'and 2 (31.8%) 3 (31.8%) Figure 16. Distnbution of all snook and red drum collected from the ponds.