Naomi Taylor. September 2008 University Of Glamorgan Project supervisor: Dr P R Wiles

Transcription

1 Impacts of intense fishing of groupers (Serranidae) as top keystone predators and the subsequent effects on the supporting reef ecosystem of Utila Island: Catch Assessment and Stomach Content Analysis Naomi Taylor September 2008 University Of Glamorgan Project supervisor: Dr P R Wiles This work was carried out in part fulfilment of the requirements for the award of degree of Master of Science in Environmental Conservation Management 5

2 Acknowledgements I wish to thank the staff and volunteers at the Utila Centre for Marine Ecology, in particular Dr Steve Box (Managing Director) and Italo Bonilla-Mejia (Head of Fisheries Research) for their continued help, support and supervision in the undertaking and completion of this project. A special thank you to the fishing community of the Cays for their cooperation in allowing assessment of their fish stocks and the assistance they gave in obtaining specimen guts. I also wish to thank Project AWARE for their interest and support in making this project happen. 6

3 Abstract More than 80% of the world s shallow reefs are severely overfished [WWF 2008] causing significant threats to coral reef ecosystems and both direct and indirect effects on the community structure of fishes and other marine organisms. Using a combination of catch assessment techniques in conjunction with stomach content analysis this study analyses the status of Grouper catch in Utila, the Bay Islands Honduras and discusses the implications and effects of artisanal fishing communities such as those in Utila. There is a global lack of species specific catch statistics and this study will Investigate into the species specific relationships between Total Length, Body circumference and Gape size as well as distinguishing dietary habits, both size and species specific. This data will provide a clear insight into the status of both the current grouper population and its future viability. Understanding and defining the trophic linkages between top keystone predatory species such as members of the Serranidae (Grouper) family and their selected prey species is the first step in creating suitable and effective management strategies in a bid to protect this precious and diverse habitat. 7

4 Contents 1. Introduction Utila Groupers Threatened status Artisanal Fisheries Existing Projects Aims and Objectives Methodology Catch Assessment Stomach Content and Gonad Analysis Abundance/Observational Dives Results Catch Assessment Total Length Catch Assessment Gape Size Catch Assessment Circumference Methods of Capture Stomach Content Analysis Abundance/Observational Dives Discussion Catch Assessment Stomach Content Analysis Conclusion References.50 Appendix I.54 Appendix II 55 Plate I.56 Plate II 57 Plate III..58 8

5 1. Introduction Globally, commercial marine species such as members of the Serranidae (Grouper) family are being overfished, with devastating ecological and economic consequences to the supporting coral reef ecosystems. Many targeted species are top predators and a decrease in their abundance will not only reduce species diversity, it could also lead not only to local extinctions of functional groups but could result in significant changes both directly and indirectly to the ecological structure, health and productivity of the reef. Groupers as a species are generally targeted by small scale artisanal fisheries, rather than the larger commercial businesses which tend to target schooling species. It has been estimated that 90% of the world s harvest of marine food is derived from the artisanal fishing industry [Randall 1993] of which groupers make up a significant component. Even as a commercially valuable species, catch statistics tend to be generalized with all grouper species summarized under one name. This lack of species specific data is preventing the clear status, both in terms of abundance, vulnerability, fecundity and distribution of the species to be identified and subsequently managed. In order to prevent these harmful effects, suitable management measures based on reliable and current stock data, along with the causes and consequences of overfishing the species in terms of their status in the tropic food Webb need to be implemented. 9

6 1.1 Utila The island of Utila is part of the Bay Islands archipelago which lies 50km off the Caribbean coast of Honduras and extends for over 130km. [Figure 1] Utila is the smallest at just 11 x 4 km of the three main islands that make up the Bay islands along with Roatan and Guanaja, and is located in a region that marks the southern end of the Meso-American Barrier Reef System (MBRS), the second largest barrier reef in the world. Figure 1, The Bay Island archipelago and its location off mainland Honduras. The MBRS supports a diverse array of fish, corals, marine mammals, reptiles and invertebrates and contributes to the stabilization and protection of the coastal landscape, maintenance of costal water quality and provides a breeding and feeding ground for marine inhabitants many of which are of commercial importance. It is of great economic importance to the island providing employment and a source of direct and indirect income on which the population of Utila rely on. 10

7 Coral reefs such as the MBRS are the most biologically diverse marine eco-systems on earth, rivaled only by the tropical rainforests on land. They occupy less than one quarter of a percent of the earth's marine environment, yet they are home to more than a quarter of all known fish species. [WWF 2007] Utila is a volcanic knoll surrounded by a collection of sandy cays that are linked by mangroves and shallow sea grass beds and is situated on the edge of the continental shelf beside a precipice that drops to over 1000m [UCME 2008]. It provides a collection of diverse marine habitats that supports a wealth of resident and visiting marine species. [Fig 2] Originally discovered by Christopher Columbus in 1502, Utila along with the rest of the Bay islands was settled by pirates and European buccaneers until the 1800 s when the British were forced to give the Bay islands to the Honduran government. As a result the native language of Utila as with the rest of the Bay Islands is English however as emigration from the mainland increases as well as from other parts of the world, the population has become a multicultural blend of white islanders, Latino mainlanders, indigenous Garifuna and Afro-Caribbean islanders as well as the influx of tourists who dramatically increase the resident population. The Cays Figure 2, The Cays: Location of Utila s two fisheries 11

8 Utila is divided into two distinct socio-economic communities both with a direct reliance on the natural resources of the island [UCME, 2008]. The main population of around 8,500 [UNPECO census 2001] is located primarily around East Harbour and is heavily dependent on dive tourism to support the local economy. A second smaller community of around 200 people, consisting predominantly of white islanders and Garifuna, is located off the western end of the island on the Cays where the economy is sustained by fishing and where Utilas two small artisanal fisheries are located. 1.2 Groupers As a species, Groupers of the family Serranidae and sub family Epinephelinae compromises of 161 species of marine fish divided into 15 genera and are one of the most commercially and ecologically important species worldwide [Heemstra & Randall, 1993]. As well as supporting commercial, recreational and artisanal fisheries throughout the world, as top level keystone predators they heavily influence the trophic web of the supporting coral reef ecosystems. However few have examined this vital relationship between the varying abundance of groupers as top predators and the subsequent effects on the abundance of prey species as well as the supporting reef ecosystem. Characteristically strong, robust and stout in build, with large mouths, the serranids are among the most important carnivorous fish of coral reefs. Varying in size from the 7ft Goliath grouper to the 1ft Coney, Groupers spend the majority of the time lurking in shallow reefs, ledges, and wrecks or slowly cruising the reef. They are not a slow species and can pick up bursts of speed; however their large heavy set bodies make them more suited to idly wandering the reef rather than long distance fast swimming. Groupers are some of the oldest fishes on coral reefs several do not reach maturity until late in life, making them particularly vulnerable to fishing before they are able to reproduce [M.Craig, Hawaii Institute of Marine Biology, 2007]. 12

9 A vast majority of the members of the Serranidae family are protogynous hermaphrodites, demonstrating a haremaic social system, where larger dominant females alter sex to become male, when no male is available. The cause is unknown but most likely to be as a result of behavioral triggers. The sex ratio of a species provides a clear indication of the status of the reef and its ability to sustain species populations. A healthy grouper population supports a 1:4 male to female ratio with an unhealthy population around a 1:12 male to female ratio. Information on gender is also particularly important for the management of the grouper, where increased mortality through fishing can directly affect sex ratio and therefore the reproductive capacity of the population. Groupers as a species also tend to spawn in large aggregations sometimes up to as many hundreds of thousands, at specific times of the year and in generally the same location, making them extremely susceptible to overfishing. Transient aggregations, where typically a larger number of fish congregate from over a wide area, make it easy for fisherman to catch a large number of a species at once, as they tend to find aggregations before anyone else. A large number of aggregations occur in countries where there are no regulations and little or no effective management to control the number of fish taken. [ 2008] In 1998 the Bay islands supported a spawning aggregation of E.striatus of approximately 10,000 and by 1991 this had declined to just 500 by 1991 due to intense fishing of the aggregations. With such dramatic declines the population abundance over a large area will be greatly affected, resulting in fewer juveniles and leaving the viability of the population in question. The first recorded disappearance of a spawning aggregation was in the 1970 s in the US Virgin islands where a large aggregation of E.striatus was lost over just a few years after discovery and there is no evidence to show that aggregations can reform. Typically demersal, they are opportunistic feeders preferring to lie in wait for prey, eating a diet of primarily fishes and crustaceans, feeding both by night and day but are most 13

10 active at dawn and dusk. The smaller serranids, in general, are primarily diurnal. [Randall 1967] They have a few fixed outer canines, numerous depressible inner teeth and heavy crushing tooth plates inside the pharynx. Their large mouths and gills form a powerful sucking system that draws their prey in from a distance, typically swallowing prey whole. They also use their mouth to dig into the sand forming shelters under rocks and ledges. Most piscivorous fish are gape-limited because they swallow prey whole and the maximum size of prey selected is determined by the mouth size of the predator [Werner, Galis, 1974, 1993] There is a serious lack of data and information regarding the diet and gape size of piscivorous fish, in particular predatory species that may prove vital in the direct and indirect success of local management plans and the rejuvenation of the reef ecosystem. The largest and most common genera in the Atlantic are Epinephelus and Mycteroperca which includes some of the most threatened species worldwide. [Fig 3] Rounded caudal fin Truncate caudal fin Epinephelus Mycteroperca Figure 3 Body forms of the Epinephelus and Mycteroperca genera 14

11 Although appearing very similar there are many distinguishing features. Members of the Epinephelus genera have a narrower body depth at the anus than at the dorsal fin, with a usually rounded caudal fin and 7-10 anal fin rays. Whereas members of the Mycteroperca have 10 to 13 anal fin rays, a caudal fin that is either truncate, emarginated or concave and have a body depth at the dorsal fin that is not more than the body depth at the anus. [Randall, 1967] The waters around Utila and the bay islands support a diverse array of grouper species from the smaller, shallow reef species such as Cephalopholis cruentatus (Grasby) and Cephalopholis fulvus (Coney) to the larger deeper species such as Mycteroperca venenosa (Yellowfin Grouper), Mycteroperca tigris (Tiger Grouper), Epinephelus guttatus ( red hind), Epinephelus morio (Red grouper) and Epinephelus striatus (Nassau grouper). However this project focuses on the main commercial species that are being landed at the Cays fisheries. Epinephelus striatus (Nassau grouper) is one of the most threatened grouper species worldwide yet it is still being landed in Utila in considerable numbers primarily due to the lack of management and education. Reaching up to 4ft in length its geographical distribution spans from Florida and the Bahamas, throughout the Caribbean, down into the Gulf of Mexico and Bermuda. It can be found resting near the bottom or hiding under ledges or in caves, it is a very inquisitive and friendly species. Usually seen with an olivebrown background and five irregular body bars, a dark band also runs diagonally from the snout, through the eye, ending at the anterior of the dorsal fin. It has the ability to dramatically darken and lighten its skin colour as well as almost losing its body bars completely and can sometimes be confused with similar species such as Epinephelus morio (Red grouper). However it can be distinguished by a dark saddle on the upper caudal peduncle and a ring of black dots around each eye. [Plate I (b)] 15

12 Mycteroperca Venenosa (Yellowfin Grouper) is one of the most abundant groupers in the Caribbean, its name meaning venomous in reference to its association with ciguatera poisoning. Its geographical distribution is the western Atlantic ranging from the southern US, down throughout the Caribbean and continuing south to Brazil, the only disruption spanning the Amazon basin. Adults are usually found on rocky and coral reefs in depths of 2 to 137m, with juveniles occurring in shallow turtle grass beds. M.venenosa is able to change colour very quickly but has two main colour morphs: a deep-water form (approx 100ft) where species tend to be bright red with an even distribution of oblong dark red blotches over the head and body and a shallower water green morph. The Caudal fins, soft dorsal and anal fins have a dark margin and white edge and M. venenosa can be easily distinguished from other grouper species through the distal third of the pectoral fins being bright yellow. [Plate I (c)] Mycteroperca tigris (Tiger Grouper) its name in reference to the nine dark diagonal body bars over a pale background similar to that of a tiger. Its head is covered in small spots and can obtain lengths of 3.5ft. It is usually seen slowly swimming amongst the shallower reef or at cleaning stations generally above 60ft, its geographical distribution spans from the Bahamas throughout the Caribbean down to south Brazil. [Plate III (a)] Epinephelus morio (Red Grouper) can be easily confused with E.striatus in its reddishbrown colouration and ability to display similar dark body banding, however it can be distinguish through its lack of saddle at the base of the caudal fin and ring of black dots around each eye. Preferring rocky bottoms it can be found in depths of ft however sometimes in shallower reefs, reaching up to 3 ft in length its geographical distribution ranges from Florida down to Brazil however it has been found to be more common in the Gulf of Mexico than the Caribbean [ P.Humann, 2007] [ Plate II (b) ] Epinephelus guttatus (Red Hind) is the smallest of the commercial species landed in and around Utila, typically 15inches it can reach lengths of up to 2ft. As a species in can be found in variety of habitats from shallow reefs to deep banks up to 330ft and is identified by its reddish spots over a pale background where the anal and caudal fins have dark- 16

13 black bands with white exterior edges as well as yellow tipped dorsal spines. Its geographical distribution spans from Florida, through the Gulf of Mexico, Caribbean down to Brazil. [Plate I (a)] Mycteroperca interstitialis (Yellowmouth Grouper) can be distinguished by the inside as well as the external corners of its mouth being bright yellow, as its name implies. Typically a uniform brown it can also display a pattern of dark dots and is found swimming amongst shallower reefs or hiding in caves and crevices at depths of up to 500ft. Its geographical distribution ranges throughout the Caribbean to Brazil; however it has be found to be more common in island waters rather than mainland coasts. [C, L Smith 1997] [Plate II (c)] Epinephelus nigritus (Warsaw Grouper) is a deep water western Atlantic species usually inhabiting rocky bottoms between ft. It is a slow growing and long lived species (up to 41 years) [Mannoch and Mason, 1987], reaching up to around 7ft. Its geographical distribution spans the Gulf of Mexico, the eastern Caribbean and south to Brazil, however recorded landing of E.nigratus in the bay islands is nonexistent due to the fact that similar fish are grouped together in fisheries data. Uniformly reddish brown in colour, it is the only Atlantic grouper to have 10 dorsal spines, where the second dorsal spine is notably elongated. Considerably little is known about the species and its population abundance due to the depth at which it s found and as a result it is listed as critically endangered by the ICUN. [Plate II (a)] All Groupers are of considerable importance and value commercially as food and sport. As highly desirable and valuable fish food, many species in particular the larger ones have been so heavily overfished that they are now endangered, in Asia grouper is such a delicacy that there is also a huge market in live grouper trade. Groupers have a long life span and do not reach maturity until later in life, this combined with the fact that most groupers spawn in large aggregations at certain times of the year make them extremely susceptible to overfishing and exploitation. 17

14 1.3 Threatened Status In 2007 a workshop for the global red list assessment of groupers was held in which the status of all grouper species was assessed. Of the 161 species, the status of 139 had never been considered. At the time 20 species were assessed to be threatened with global extinction (Critically Endangered (CR), Endangered (EN) and Vulnerable (VU)), with a further 22 listed a Nearly Threatened (NT), species close to the threatened thresholds, or that would be threatened without ongoing conservation measures. 48 of the 161 species were found to be Data Deficient (DD), where no evaluation was undertaken due to insufficient data, some of which are commercially important species. The results indicate that there is a global lack of accurate and reliable data to fully comprehend the impact and scale of overfishing of groupers, an issue that needs to be urgently addressed. The workshop recommend a further 22 species to be put forward onto the ICUN red list. Of the 161 species, 27 are now currently listed as Critically Endangered, Endangered and Vulnerable on the ICUN Red list, The results of the workshop equate to that twenty percent of all categorized species are threatened, with a further nineteen percent listed as NT and at least 50% of threatened species spawn in aggregations [Sadovy, GWSG, 2007] Of the seven species in consideration in this project all but one (E.guttatus) features on the ICUN red list, with statuses ranging from critically endangered to Nearly Threatened. [Table 1] 18

15 Table 1: ICUN Red list status of each species to be assessed Species Status Exploitation Congitory Behavior Epinephelus nigritus CR A2d +3d Heavily fished and Yes management not very effective Epinephelus striatus EN A2ad Once common locally now Yes rare, targeted and unmanaged Mycteroperca VU A2d +3d Not naturally common, Yes interstitialis unmanaged Mycteroperca Venenosa NT Heavily fish, very common Yes Epinephelus morio NT Heavily fished Yes Mycteroperca tigris NT Commercially less Yes important Epinephelus guttatus LC Naturally abundant Yes E.guttatus does not feature on the ICUN red list, however was assessed by the workshop to be of least concern due to its natural abundance levels despite being heavily fished throughout the Caribbean. It was noted however that all species abundance are in decline due to intense pressures and exploitation from overfishing, combined with a lack of management or effective management and protection. 19

16 1.4 Artisanal fisheries The FAO Glossary defines artisanal fisheries as being: "traditional fisheries involving fishing households (as opposed to commercial companies), using relatively small amount of capital and energy, relatively small fishing vessels (if any), making short fishing trips, close to shore, mainly for local consumption. In practice, definition varies between countries. Artisanal fisheries can be subsistence or commercial fisheries, providing for local consumption or export. They are sometimes referred to as small-scale fisheries". The two Utilian /Cayan fisheries are classed as artisanal; traditional fisheries involving fishing households, using a small amount of capital, and small vessels. However in practice they operate on a commercial basis with over approximately 98% of landed catch being exported to mainland Honduras and on to the United States [Fig 4]. An extremely small proportion of the catch is bought by the small local population and any product (typically by catch) not suitable for export such as juveniles or non commercial species e.g. Grunts are consumed by the local garifuna population. Figure 4: Landed catch on ice before export to mainland Honduras and then onto the US Both fisheries are of a very different nature, Fishery 1, the main and more commercial deals only in fish stocks and owns its own ice making machines, with over 1000lbs of fish being caught each week. The second more diverse primarily deals in conch and 20

17 lobster caught by divers, however a large quantity of large fish such as members of the Serranidae family are caught as by catch and fish stocks play a vital role in the fisheries survival. It is an independent business, with its own generator to refill scuba tanks, renting out fishing dories, diving equipment and ice which it buys in, enabling the fishermen to fish successfully and in turn generate more profit for the fishery. Although rivals, both fisheries coexist successfully due to their different focuses. The weather plays a large part in the productivity of each fishery. Usually the focus is on the main fishery and large amounts of different species are caught for export. When the wind increases, traditional methods such as hook and line and fish traps [Fig 5] are least effective and the majority of fisherman switch to diving for conch and lobster, also using a spear gun to catch larger fish and as a result focus switches to supporting the second fishery. Figure 5: Fish Traps made from sticks and wire mesh In many countries including Utila, small-scale/artisanal fisheries are developing fast expanding markets (e.g. export markets) and adopting new technologies such as GPS and fish finders. However many others are experiencing difficulties, not able to invest financially in order to compete with rivals. Although times are hard for artisanal fisherman not only in Utila but worldwide, the successful ones and ones who will be able to survive the hard times ahead are those financially independent enough to own their own boat and that can invest in technology to find the ever dwindling fish stocks. 21

18 Opinions on the dwindling fish stocks in the waters of Utila are unanimate. There is a serious decline of the abundance of fish species and fishermen have to go ever increasingly further afield to make a living. However the solution to the problem is not so clear. Many recognize the need for management and are willing to participate in methods that will ensure the continued maintenance of fish stocks however due to diverse social and religious backgrounds there are others that believe the problem will be solved for them. Artisanal fisheries are often thought to be different; most likely because of a lack of data and understanding on real trends and socio-economic impact. Their unconventionality and typical physical distribution as well as many social and financial constraints make it difficult to implement management strategies and control methods. However the survival of the artisanal fishing communities in and around Utila depends on an understanding of the trophic status of the reef ecosystem. Determining the diet of top predatory keystone species is the first step in assessing the impact of intense fishing by small scale fisheries and its subsequent affects on the reef. Through establishing the main prey species of these top predators, we can then assess what impact the decline and potential loss of this species along with the change in abundance of prey species will have on all dependants of the reef. This data will then allow for a practical and effective management plan to be devised that will not only help fish stocks to recover and the general status of the reef to improve but will help sustain and potentially improve the success of local fishing communities. 1.5 Existing Projects A study led by Peter Mumby of the University of Exeter was undertaken in Exuma Cays Land and Sea Park in the Bahamas to establish how effective marine reserves could be at protecting key predatory species in particular the Nassau Grouper (an economically and culturally important Caribbean species). In particular researchers were interested in how an increased abundance of predators may affect the supporting coral reef ecosystem, for example an increase in abundance of predatory species could have a detrimental effect on population numbers of herbivores, thus causing seaweed and algae blooms and 22

19 overwhelm corals. The park was established in 1959 and became a no take area, closed to fishing in It was predicted that without the occurrence of fishing the Nassau grouper population would thrive resulting in a significant decrease in the number of parrotfish, the groupers main diet and one of the few species that graze on macroalgae. This would then result in a subsequent increase in the distribution and abundance of macroalgae on the reef. In fact the study produced the opposite effect. The result was an increase in the Nassau grouper population as expected however this unexpectedly resulted in a dramatic increase in the abundance of large parrotfish that had outgrown the dietary limits of even the largest groupers. Protection of the larger parrotfish from incidental fishing as a result of the marine park resulted in a doubling of grazing within the park leading to a fourfold reduction in seaweed cover compared to areas outside the park. The study clearly indicates a distinct relationship between groupers, parrotfish, algae and coral reefs that must continue to ensure the reef ecosystem survival. Another study entitled [Ontogenetic changes in the diet of the coral reef grouper Plectropomus leopardus : patterns in taxa, size and habitat of prey] was conducted by Jill St John, in the Great Barrier Reef, Australia. The study aimed to investigate the ontogenetic dietary relationship between a predatory species and their prey. Specimens of coral trout were collected over the summers of 1991 and 1992, ranging from 4.7 to 57.3cm SL (standard length) and the stomach contents and diets were examined. The results identified 422 different prey specimens of 28 different families, of which 3 families, Clupeidae, Pomacentridae and Labridae, represented more than 60% of the diet. The study concluded that juvenile (up to 20cm SL) and adult coral trout, P.Lepardus have very distinct diets with juveniles consuming a high proportion of benthic dwelling crustaceans, eg penaeid shrimps, whereas adults were almost entirely piscivourous. The dietary shift in the type, species composition, length and shape of prey occurred at approximately 20cm SL just prior to the onset of maturity. 23

20 Predation rates were related to the size and gape of the predator in both juveniles and small adults and in specimens up to 35cm SL the range of prey sizes increased with the size of predator length. However after 35cm SL the composition and length of the prey did not alter but in general larger coral trout fed optimally on deeper bodied fish whereas juveniles with smaller gapes consumed slender prey. All size related predation was found to be altered by the occurrence of large visible schools of small fish. 1.6 Aims and Objectives The aim of this project is to assess the impacts on the abundance of a top predatory keystone species, subjected to intense fishing and exploitation by small scale fisheries and the subsequent affects on the supporting reef ecosystem. Specifically this project will undertake a catch assessment of all members of the Serranidae family to be landed over a specific period in order to assess the abundance and composition of landed species. This will be supported by stomach content analysis in order to determine prey species and the abundance in which it s consumed as well identify any specific dietary shifts between species. The study will include details on total length, body circumference and gape size in order to evaluate any correlation between total body length and gape size of the predatory species and total body length and species of the prey as well as investigating if the size class of a species and its corresponding gape size determines prey species and the abundance in which its consumed. Stomach content analysis will allow prey species to be identified to family if not species level, with the hope of establishing any specific species dietary shifts, However the success of the analysis will be heavily dependent on the degree of digestion within the stomach. The entire guts of each specimen, not just the stomach allowing gonad analysis to be conducted and a sex ration per genera established. The overall objective of the study being to identify the ramifications that overfishing is having on the abundance and diet of 24

21 predatory species and how this impacts on the relative composition of prey species and the reef ecosystem as a whole. These measurements could form the basis of samples taken regularly over a number of years, that can then be used to establish the growth of the fish, the age structure of the population, the age at which the fish become liable to capture, and how quickly the population is reduced as a result of fishing and natural mortality. 25

22 2 Methods The study was undertaken and data collected throughout July and August Due to the weather conditions at time of assessment and overall general depreciation of fish stocks, catch abundance was low and as a result all species of the family Serranidae that were landed were assessed and recorded. This included the smaller commercial species Epinephelus guttatus (Red hind) as well as the larger Mycteroperca Venenosa (Yellowfin Grouper), Mycteroperca tigris (Tiger Grouper), Epinephelus morio (Red Grouper), Mycteroperca interstitialis (Yellowmouth Grouper), Epinephelus striatus (Nassau Grouper) and the rarer, less common Epinephelus nigritus (Warsaw Grouper). The majority of specimens assessed went through the second, smaller but more diverse fishery on the Cays, which also supports Conch and Lobster divers, as well as traditional fishing methods of Hook and line and Fish traps. This was important at the time of assessment because of the varying weather conditions. Full analysis and evaluation of the methods used to catch specimens can be found in the results section. 2.1 Catch Assessment Once a catch had been landed, permission from the fisherman to measure specimens and obtain the guts was requested. If obtained all members of the Serranidae family were separated from the catch, allowing the fisherman to continue gutting and processing the remainder of the catch reducing the inconvenience to the fisherman at all possible cost. Each specimen was identified to species level and assigned a unique and individual specimen number, recorded on a prepared table. 26

23 The total length of each fish was measured and recorded to the nearest cm, by placing each specimen head first onto a pre-prepared fish board, firmly holding the specimen down and extending the caudal fin [Fig 6] where; TL is defined as the measurement between the tip of the nose to the end of the caudal fin Figure 6: Establishing the Total Length of M.venenosa Circumference at fattest was then measured and recorded to the nearest cm using a tape [Fig 7] where; Circumference at fattest is defined as the measurement around the fattest part of the body located at the base of the pectoral fins. This was followed by Gape size which was measured and recorded to the nearest mm using calipers, which were adjusted to the size of the rear of the mouth [Fig 8] where; Gape size is defined as the narrowest lateral measurement inside the mouth Each specimen was subsequently photographed using the fish board as an appropriate scale and lined up for gutting. 27

24 Figure 7(Left) : Measuring the body circumference of M.venenosa. Figure 8 (Right): Measuring the Gape of M.venenosa Gutting was performed by a variety of individuals predominantly by garifuna but also by the fisherman themselves or in some cases the fisherman s young sons, all with a different skill level which resulted in varying completeness of samples. [Fig 9] As specimens were gutted, the guts were collected in plastic zip lock bags and labeled with species and specimen number. Figure 9: Fisherman gutting E.striatus In some instances when the abundance of landed Serranidae specimens were low and individually unique and identifiable, species were not measured as the catch was landed and only the guts were immediately obtained and clearly labeled. Specimens were measured once they had been transported and processed through the fishery before they 28

25 were to be packed on ice. This proved the most effective method when possible due to the confined spaces of the pier in which the catch was landed and the time constraints imposed by the fisherman, it also allowed for more time with each specimen and accurate measurements. In cases where the catch had been cleaned at sea, which often occurred, it was not possible to obtain the guts. In these instances specimens were measured and recorded once they had reached the fishery to allow for a full assessment of the status of the Serranidae family. 2.2 Stomach Content and Gonad Analysis Analysis of specimen stomach contents were completed the same day as collection, with samples refrigerated immediately after acquirement. At time of analysis each sample in order of specimen number, was photographed on a white dissection tile against a suitable scale and any general observations including protruding prey, size or condition of guts were recorded for later evaluation. The Identification of the presence of gonads within the sample was undertaken initially due to the variance in the individual gutter and the according skill level, which greatly affected the quality and completeness of samples. If gonads were present the sex of the specimen was determined and recorded through gonads analysis in accordance with the guidelines for the use of fishes in research by The American Fisheries Society, the American Society of Ichthyologists and Herpetologists, and the American Institute of Fisheries Research Biologists (2002) and the Manual of Methods for the MBRS synoptic monitoring program (2003) Gonad analysis was conducted prior to stomach content analysis as to avoid contamination and misidentification from stomach acid and digested prey. Gonads were identified within the gut mass where applicable and assessed to be either male or female 29

26 and recorded. Examples of gonads can be seen in Fig 10 and Fig 11. In a significant number of samples, gonads were not available due to the gutting process and varying skill level of the gutter. Fig 10 (Left) : Female gonads from a specimen of E.striatus. Fig 11 (Right): Female gonads from a specimen of M.venenosa For each sample the stomach was dissected and the contents removed onto a dissection tile using a scalpel and full dissection kit. [Fig 12] The contents were analysed and in the case of whole prey specimens were separated and removed from the sample, with the aim of identification to the lowest possible taxonomic level dependant on the degree of digestion. In the majority of cases family was immediately obvious and confirmed using a range of keys and Id resources, a list of which can be found in the bibliography. Identification to species level was achieved through microscopic analysis of identifying features such as scale coloration, dorsal and anal fin counts as well as analysis of any jaw and mouth parts, this was undertaken in conjunction with suitable identification keys. If prey species identification was not immediately possible, prey specimens were fixed in 70% alcohol for further analysis at a later date, however in some cases species level identification proved impossible due to degree of digestion and samples are recorded to family level only. Prey masses were not collected because of the varying degrees of digestion rendering the measurements meaningless. 30

27 Figure 12: Dissection of the stomach of M.venenosa In cases where prey specimens were heavily digested and body shape and form was not visible, any identifying features including spines, pectoral fins and jaws were removed for microscopic analysis in conjunction with suitable keys. Once identification had been completed and confirmed prey specimens were recorded, photographed and measured. Measurements taken of prey species were dependant on degree of digestion. In piscivorous samples, if the back bone was unbroken the standard length was measured to the nearest cm and if at least one caudal fin was intact this subsequently allowed the total length of the specimen to be established to the nearest cm. A body depth value of prey species if obtainable proved vital in determining a relationship between predator gape size and prey species. Body depth was measured dorso-ventrally from the leading edge of the dorsal fin dependant on degree of digestion. In non piscivorous prey specimens, such as crustaceans and squid (fancy word for squid), specimens were again identified to either family or species level through microscopic analysis of identifying features in conjunction with suitable keys. Total body length and general observations were recorded if obtainable, again dependant on degree of digestion. 31

28 2.3 Abundance/Observation Dives A number of abundance and observational survey dives were carried out based on AGRRA methodology. AGRRA (Atlantic and Gulf Reef Rapid Assessment) incorporates two methods that characterize fish populations, Belt transects and a rover diver method, both of which were undertaken. Belt transects were carried out using a 1m t-bar held at arms length and marked at 5cm intervals to assist with approximation of size. Belt transects of 2x25m were visualized, where 25m is equivalent to 15fin kick cycles and the occurrence and size of each specimen observed within the transect recorded. Each 2m segment of belt transect is surveyed separately and uniform attention was given to each successive 2m segment of the transect whilst surveying. As with the AGRRA method specimen lengths were recorded in specific size categories (0-5 cm, 6-10 cm, cm, cm, cm, >40 cm), however for specimens in the last category(>40cm) an approximate size was given to give more detailed results. All results were recorded on a pre prepared table drawn on an underwater slate, that also accommodated any behavioral patterns or general observations that may have been noted. In Rover diver method surveys the occurrence of observed specimens and approximate length were recorded however this was not within the confines of a pre determined belt transect but over a whole dive site. This is a technique used by REEF (Reef Environmental Education Foundation) in maintain their fish abundance database for the entire Caribbean. This will provide an indication as to the abundance, location and size of the current population. 32

29 3. Results Data was collected over July and August 2008 from the two fisheries located on the Cays, on the South Western tip of Utila. The full data set containing, date landed, fishery, fisherman etc is available on request. 3.1Catch assessment Total Length In total 135 specimens of the Serranidae family over 7 genera were measured and recorded immediately after landing over the duration of the study.[fig 13] Figure 13: Graph showing the abundance of each landed species throughout the duration of the study M.venenosa, N=61, Total of N=45.2%, TL 27±78cm, Mean 53.5cm, (σ) E.guttatus, N=22, % Total of N = 16.3%, TL 27±47cm, Mean 35cm, σ=4.49. E.striatus, N=20, % Total of N=14.8%, TL 32±84cm, Mean 54.2cm, σ= E.morio, N=10, % Total of N =7.4%, TL 32±68cm, Mean 49.4cm, σ= M.tigris, N=9, % Total of N =6.7%, TL 33±51cm, Mean 42cm, σ=5.52. M.interstitialis, N=9, % Total of N = 6.7%, TL 36±60, Mean 49.8cm, σ=6.92. E.nigratus, N=4, % Total of N =3%, TL76±85cm, Mean 80cm, σ=

30 Figure 14: Graph showing the varying size distribution of the catch by species It can be seen in Fig 14 that there is a significant difference in the size classes of species; however this trend does follow the natural order of species size with E.guttatus being the smallest species and E.nigratus the largest of the landed species. The results however do suggest that the mean TL of landed species is particularly low, with all but 3 species having a mean TL of below 50cm and two of the three over 50cm being under 55cm Mean length. This indicates that a substantially higher number of smaller juvenile fish are being landed throughout all Grouper species which could lead to drastically dwindling fish stocks and significantly affecting the reproductive capability of the species. A low Mean TL value would however be expected for the species E.guttatus, who typically only reach a TL of around 38cm and so the size distribution of the catch for this species does represent a typical and sustainable range. 34

31 Looking at the size distribution of species [Fig 14] three individual specimens from the whole catch assessment have been identified as being outside normal bounds in terms of the total length of the catch per species. Species number 86, a specimen of E.guttatus TL 47cm and Species number 85, E.striatus, TL 84cm were identified to be above the normal bounds of this catch. Sp86 is a particularly large specimen of a species that typically reaches 38cm TL, however looking at the results as a whole only 3 specimens of E.guttatus landed were above this typical maximum size. Sp 85 although identified as extremely large within the sample size, at 84cm TL it is still far off reaching its maximum TL of around 121cm and within the sample only 3 specimens had obtained TL of 70cm and above. Species number 42, M.interstitialis; TL 36cm on the other hand was identified as being significantly below the average bounds in terms of TL, indicating that this specimen was a particularly young juvenile. The Mean TL of this species is however 49.8 which is a reasonable size in a species who s known maximum TL are 80cm. 3.2 Catch Assessment Gape Size Gape size was taken from 123 out of the 135 specimens and measured as the narrowest lateral measurement inside the mouth when the mouth. Measurements were unable to be obtained from 2 individuals due to the time constraints imposed by the fishermen. It must be noted that these measurements were taken when the mouth was not open and expanded. In the cases where specimens were landed with an open/expanded mouth, the narrowest lateral measurement was recorded however measurements were identified as being abnormal to the data set and have been removed from the analysis to prevent inaccurate results. 35

32 Gape Size Report Species N Mean Std. Deviation Minimum Maximum M.venenosa E.striatus E.guttatus M. tigris E.morio M.interstitialis E.nigratus Total Table 2: Showing the Mean, Standard deviation, Minimum and Maximum Gape size values for each species landed. In [Table 2] the size distribution of specimen gape size per species can be seen. The results indicate that there is a difference in Gape size of just over 10mm in the different specie demographics with the Mean gape sizes ranging from 33.1 mm in E.guttatus to a Mean of 43.9mm in E.striatus. The Mean gape size of E.nigratus specimens is considerably larger at 66mm however this figure is taken from one individual as the other 3 specimens had open mouths and the data was excluded to give a fair representation. With a standard deviation σ =6.46 over a data set of N=17, E.guttatus proves to be the most consistent data set and E.striatus, N=19, σ= the least consistent however this figure is offset by the fact that this data set has the largest range of specimens in terms of TL. It is however reasonable to make the conclusion that E.nigratus has a definitively larger gape size than other Grouper species measured due to its naturally occurring size and this can be seen in Figure

33 Figure 15: Distribution of Gape sizes throughout the different species landed. There is a distinct positive correlation for all species between the Total length of an individual and its Gape size. [Fig 16] However this correlation is least prominent is the species M.interstitialis closely followed by E.guttatus and being most noticeable in E.striatus. These results are understandable in the case of E.guttatus due to its naturally occurring size and the data set for E.striatus represents an even sample of the whole population size of the species, suggesting a continued and sustained growth throughout their life span. The results for M.interstitialis however indicate a slow growth rate within the species. 37

34 Figure 16: Graph showing the relationship between Total Length and Gape size for each species; also include a line of best fit. 3.3 Catch Assessment Body Circumference In the assessment of Body circumference all specimens were measured once cleaned (Guts removed). [Table 3] An interesting result showed that M.tigris had an unusually low Mean Body circumference at 24.29cm with a σ=3.9 compared to similar sized species such as M.interstitialis Mean 32.5, σ=3.77, E.morio Mean 35.1, σ=9.8 and M.venenosa Mean 35.48cm, σ=7.3. The smallest specimen of M.tigris being TL33cm, 38

35 Circumference 20cm and Gape 35mm and in comparison to a specimen of E.guttatus TL=33cm, Circumference = 25, Gape = 26mm of the same TL, M.tigris is comparatively thinner. E.nigratus as expected demonstrated the largest Body circumference with a Mean of 53.25, σ=3.4. Circumference Report Species N Mean Std. Deviation Minimum Maximum M.venenosa E.striatus E.guttatus M. tigris E.morio M.interstitialis E.nigratus Total Table 3: Showing the Mean, Standard deviation, minimum and maximum circumference measurements per species. As with Gape size there is a distinct positive correlation between Total length and Body circumference. [Fig 17] The bigger the species the stockier it is. Again M.interstitialis shows the least dramatic increase within all species in Body circumference with the increase in TL. E.striatus shows the most dramatic increase in circumference increasing from a circumference of approximately 29cm at TL 42, to 60cm at TL84cm, proportionally doubling its body circumference with its age. 39

36 Figure 17: Graph showing the relationship between total length and body circumference for each species landed; includes a line of best fit for each species. 3.4 Methods of Capture Of the specimens assessed 103 were caught by scuba diving, 28 by Hook and Line and 4 by fish traps. From [Fig 18] it is clear that there is a definitive change in the fishing methods used over the duration of the study. At the start and through the majority of the study Diving was the only fishing method being used and this was as a result of the weather conditions. Strong winds 40

37 prevented the use of conventional methods such as Hook and Long line and fish traps. The dramatic decline in fish caught using a spear gun between the 30 th July and 1st August coincides with a large storm that occurred over the Bay Islands. It can be seen that as the weather improves and the wind decreases the general abundance of specimens caught using a spear gun and diving declines and a definitive point is reached when on the 12/08/2008 fishermen begin to use Hook and lines again, with a good success rate. Fish traps are not used until the 14/08/08 when the wind speed ceased, however the end of the study period shows a time of erratic behavior with all methods being used and to varying degrees of success and it can be concluded that fishing success rates are heavily dependent on weather conditions. Figure 18: Time Series Analysis demonstrating the different fishing methods used over the course of the study 41

38 3.5 Stomach Content Analysis Results Of the 135 specimens assessed, the guts were obtained for 61 individual specimens over the 7 genera. [Fig 19] Of the 61 samples 32 proved to be empty, containing no prey species however 18 different prey species consisting of both fishes, crustaceans, cephalopods and gastropods were identified along with 1 piece plastic in the remaining 29 samples. Just over 50% (32) of the stomachs proved to be empty and contained no prey species. Figure 19: Abundance of Stomachs containing prey items and those that are empty Mycteroperca Venenosa; YELLOWFIN GROUPER; 25 Specimens; 27-74cm TL; 14 Empty Stomach content analysis was conducted on 25 specimens ranging from 27-74cm TL, with gape sizes of 11-69mm and 79mm open. Gonad analysis showed 10 females, 4 males and 11 specimens missing gonads rendering sexing impossible. Specimens were caught through a range of methods, 13 by spear gun, 11 by hook and line and 1 via a fish trap. 42

39 Results presented 2 virtually complete Chromis cyaneus (Blue Chromis) 7 and 9 cm SL, obtained from the stomachs of specimens 38 and 41cm respectively. Prey specimens were distinguished between the similar Chromis multilineata (Brown Chromis) [Plate III (b)] by colouration of remaining scales. 2 large specimens of Clepticus parrae (Creole wrasse) 16cm and 26cm TL were recovered from specimens 58 and 74cm TL respectively [Fig 20]. Both samples were protruding from the rear of the stomachs with the later sample having ripped the stomach lining and encompassed itself around the exterior of the stomach due to its size. Samples were almost complete except from the head/jaw which was absent. A segment of digested fish meat from a 57cm specimen was identified to Scaridae taxonomic level from remaining pectoral fins. Large portions of Sarda sarda (Bonito) [Plate III (c)] were found in two specimens caught using a Hook and line method of fishing. It was assumed and confirmed that Bonito was used as bait on the hook as naturally they are fairly large and fast species that would be unable to be caught by M.venenosa. A 35cm TL approx Bonito was gathered from a 65cm specimen of M.venenosa. The sample was found in 3 distinct pieces that formed an almost complete Bonito up to and including the gill rakers. The second sample of Bonito measured approximately 20cm TL and was obtained from the stomach of a 63cm M.venenosa along with an almost complete 11cm TL juvenile Ocyurus chrysurus (Yellowtail snapper). A general observation that can be made is that it appears that M.venenosa initially capture the prey with a bite to the lower jaw and then follow to swallow their prey whole. Chromis cyaneus (2) Clepticus parrae (2) Sarda sarda (2) Ocyurus chrysurus (juvenile) Scaridae sp Unidentified fish meat Unidentified spine Figure 20: Clepticus parrae (Creole wrasse) in the stomach of M.venenosa 43

40 Epinephelus striatus NASSAU GROUPER; 13 Specimens; 41-84cm TL; 4 Empty The stomach contents of 13 specimens were assessed ranging from 41 to 84 cm TL, with corresponding gape sizes 32-72mm, and 75mm open. 12 specimens were caught with a spear gun and 1 through the use of a fish trap. Gonad analysis showed 9 female and 4 male specimens. Results of stomach content analysis presented Caranx ruber ( Bar jack) measuring 10cm TL and a 9cm TL Chaetodon capistratus (Fore eye butterfly fish) was recovered from a 55cm TL specimen. A 12cm TL Holocentrus sp (Squirrelfish) was obtained from a 57cm specimen and the body of a 10cm squid was recovered from a 72cm specimen.[ Fig 21] An unusual piece of white plastic was found in the stomach of a 48cm TL specimen along with a King crab leg joint in a very large 84cm TL specimen, weighing approx 25LBs however the stomach appeared to be infected with possible Microsporidiosis. [Fig ] A general observation made was that stomach of the smallest specimen (41cm TL) appeared to be full however was empty, although it proved extremely thick when dissected. Caranx ruber Chaetodon capistratus Holocentrus sp Lithodidae sp Reef crab (2) Cephalopods Squid Unidentifiable fish meat (3) Figure 21: Body of a squid found in E.srtiatus 44

41 Epinephelus morio RED GROUPER; 4 Specimens; 41-63cm TL; 3 Empty Stomach content analysis was conducted on the stomachs of 4 specimens ranging from 41-63cm TL, with corresponding gape sizes 27-48mm. 1 specimen was caught using a spear gun and 3 via hook and line. All gut samples contained no gonads proving sexing impossible.. 3 stomach samples were found to be empty however the stomach of smallest specimen (41cm TL) contained 6 items, 4 juvenile grunts ranging from 5-2cm in length, a cleaner shrimp and a small reef crab. [Fig 22] Haemulidae sp (juvenile) (4) Reef crab Shrimp sp Figure 22: 4 juvenile grunts from the stomach of E.morio Epinephelus guttatus RED HIND; 12 specimens; 32-47cm TL; 7 empty; The stomach contents of 12 specimens were assessed ranging from 32-47cm TL, with corresponding gape sizes of 20-41mm, with 6 open samples. Specimens were caught through a variety of methods, 7 caught with a spear gun whilst diving, 4 by hook and line, and 1 via a fish trap. Gonad analysis results showed 3 male, 4 female and 5 specimens without gonads. In intriguing result was found when a 14 by 5cm piece of conch meat was found in the stomach of a 33cm TL specimen with a 26mm gape. [Fig 23] The prey had completely perforated and ripped through the stomach of the small specimen. As the specimen was caught by a diver with a spear gun, primarily aiming for conch and lobster, it can be 45

42 assumed that as an opportunistic species the specimen stole the conch meat from the scuba diver. Fishermen use a metal tool to obtain the conch meat meaning E.guttatus would be unable to obtain the conch meat through means of their own. The body of a Holocentrus sp (Squirrelfish) [Plate III (d)] was identified from its large eye socket and spiny vertebrate was found in the stomach of a 37cm TL specimen with a corresponding gape of 34mm. A 6 cm jaw and spine of a Juvenile spotted moray eel was recovered from a 33cm TL specimen, along with two arrow crab legs and a large fragment of unidentifiable fish meat. The largest specimen (47cm TL) contained a 5cm small red reef crab that was found mostly undigested with body and legs intact. Strombus sp Gymnothorax moringa (juvenile) Holocentrus sp Stenorhynchus seticornis Reef crab Unidentified fish meat (3) Figure 23: Conch meat found in the stomach of a small E.guttatus Mycteroperca tigris TIGER GROUPER; 3 specimens; 36-41cm TL; 2 empty; Stomach content analysis was conducted on 3 specimens ranging from 36-41cm TL, with corresponding gape sizes of 26-40mm. All specimens were caught by divers with a spear gun and through gonad analysis 2 were assessed to be male and one specimen was found to be without gonads rendering sexing impossible. A 12cm complete Caranx ruber (Bar jack) was obtained from the stomach of a 36cm TL specimen with a corresponding 26mm gape.[fig 24] The prey had perforated and ripped the stomach of the predator species. Caranx ruber 46

43 Figure 24: Caranx ruber (Bar jack) from the stomach of M.tigris Mycteroperca interstitialis; YELLOWMOUTH GROUPER; 1 specimen; 50cm TL; 0 empty Stomach content analysis was conducted on one specimen of M.interstitialis, 50cm TL with a corresponding gape size of 33mm. The specimen had no gonads meaning sexing was not possible and a large fragment of unidentifiable fish meat was found in the specimens stomach. Unidentifiable fish meat Epinephelus nigritus; WARSAW GROUPER; 3 Specimens; 76-85cm TL; 3 empty; The stomach contents of 3 specimens of E.nigratus ranging from 76-85cm TL with corresponding gape sizes of 61, 81 and 85mm were assessed, the latter two gape measurements are taken from specimens with open mouths. All specimens were found to have empty stomachs and unfortunately all specimens were without gonads and sexing was not possible. The discovery of the E.nigratus in the water around Utila and the Bay islands is very important as there are no previous recorded landings of this species within the Bay Islands. 47

44 The results indicate that there is no specific dietary shift within size classes of species, as both large and small specimens are seen to be consuming the same prey items. Groupers as a species are opportunistic feeders and this is supported by examples of smaller species consuming large prey items that have then continued to perforate the stomach. An example was seen with a specimen of E.guttatus, (TL 33cm Gape 26mm) where it had consumed an extremely large piece of conch meat, splitting the stomach wall and that was approximately 3 times the size of the resting stomach. The prey item was almost half the specimen s total body length (14 x 5cm) and double the specimens closed gape size. Of the 61 samples of guts collected 41% (25) were obtained without guts and thus rendered sexing impossible, this was as previously explained due to the varying skill levels of the gutters. Over all 7 genera 21% (13) specimens were found to be male and 38% (23) found to be female, a breakdown of gonad analysis by species can be seen in Table 4. Table 4: Results of Gonad Analysis Gonad Analysis Male Female No Gonads Epinephelus guttatus Epinephelus morio Epinephelus nigritus Epinephelus striatus Mycteroperca interstitialis Mycteroperca tigris Mycteroperca venenosa Total

45 3.6 Observational Dives Dive Site Figure 25: Map of Utila showing the 6 dive sites used and reprsented by a red star Observational/Abundance dives were conducted at 6 sites around the Island of Utila with an aim to record the number of species observed, estimating their TL and noting any behavioural characteristics. Where a species is observed over 40cm TL an approximate length is estimated using a T bar and recorded.[fig 25] Table 5: Results of Abundance/Observational dives of 6 sites Site 1: Blackish Point Species >40 Observational Notes M.bonaci 58 Cruising the Drop off M.venenosa 42 E.cruentatus 2 1 Observed in rocky reefs Site 2: Jacks Bight Species >40 Observational Notes M.bonaci 1 E.morio 57 Seen in the depths E.cruentatus 2 1 Observed in rocky reefs 49

46 Site 3: Teds Point Species >40 Observational Notes M.bonaci M.venenosa E.cruentatus Site 4: Black Coral Wall Species >40 Observational Notes M.bonaci 55 Hiding under a ledge M.venenosa 1 1 M.tigris 2 42 At a cleaning station E.cruentatus Observed in rocky reefs Site 5: Stingray Point Species >40 Observational Notes M.bonaci M.venenosa E.cruentatus Observed in rocky reefs Site 6: Raggedy Cay Species >40 Observational Notes M.bonaci M.venenosa E.cruentatus Most notable is the occurrence of two previously un-discussed species of grouper, Mycteroperca bonaci (Black Grouper) and Epinephelus cruentatus (Grasby). M.bonaci is a similar size species to that of M.venenosa and also demonstrating a yellow margin to its pectoral fin, however as its name suggests predominately black in its colouring. Found commonly around the waters of the Bay Islands it however rarely 50

47 caught by the fishermen of the Cays and as shown none were landed over the duration of the study. [Table 5] E.cruentatus is a small non commercial species reaching a Total length of around 15-20cm. Abundantly found in shallow rocky reefs, hiding in small holes, under ledges etc, it is not targeted by the fishermen of the Cays due to its small size and the lack of commercial demand. It can be seen that on two specific dives no groupers were observed and this was notably due to the substrate of the sea bed. At Teds Point the majority of the sea bed was sand, a habitat that is known not to be suited to groupers, preferring rocky crevasses and ledges to hide under. Raggedy Cay was also not a suitable habitat, consisting of shallow waters with a sea grass bed floor. Larger species of Grouper such as M.bonaci and M.venenosa were predominately seen to the North and East of the Island where there is a rocky wall and drop off rather than the West where water becomes shallower with a mixture of sand and sea grass beds. 4. Discussion 4.1 Catch Assessment In assessing the status of the catch we must consider the size of the fishes being landed and how this will affect the reproductive capability of the species. As the results have shown, a large number of the landed catch were relatively small in TL for each species and this could indicate that specimens have not yet reached maturity and are unable to reproduce. It has been shown that the species E.striatus is reproductively mature from approximately 4 years of age, around 40-45cm TL, with most mature by 50cm TL (7 Years). From the results of this study, this indicates that 40% (TL<50cm) of the landed catch of E.striatus had yet to reach sexual maturity, and a further 35% (TL 50-60cm) were at their 51

48 reproductive prime. It must also be noted that the species E.striatus has never been definitively shown to be protogynous despite being known to aggregate (Shapiro 1987) In the case of E.morio, where females mature at approximately 35-50cm TL, 4-6 years of age, 50% of the landed catch have a TL<50cm.Indicating that they are being removed at a vital stage in their development with possible devastating consequences for their species if this rate is to continue. Females are however known to reach their maximum reproductive potential between the ages of 8-12 years. (Heemstra and Randall 1993). Thompson and Munro (1974) estimated that M.venenosa are approximately 4 years of age at 46-57cm TL, and 10 years at 70cm TL, with females maturing at approximately 51cm TL (Garcia et al 1994). This suggests that 34% of the landed specimens of M.venenosa had yet to reach sexual maturity (TL<51cm), and only 8% were 10 years or older (TL>70cm). Through further analysis demonstrates that there is a definitive positive relationship between the Total Length of all Grouper species and its corresponding Gape size. Fig 16.The correlation is however less prominent in some species such as M.interstitialis and E.guttatus and more definitive in species such as E.striatus, M.venenosa and M.tigris. The results of E.nigratus cannot be included in the comparison due to the small sample size and confirmation of all results would be provided by a larger data set for each species. The abundance and size distribution results suggest that the majority of the catch landed were either not yet fully mature and/or at the most reproductively productive. Honduras as a nation produce 16, 894 tons of fish in 2006 exporting product worth over $87, 411 US dollars [FAO World fisheries Production 2006]. These figures only account for a small proportion of the figures as most do not include fish stocks landed by small scale and artisanal fisheries and only the purchasers of exported fish stocks has a legal obligation to report the amount of fish stocks being traded. If this trend is to continue at 52

49 rates such as these the reproductive potential and fecundity of all these grouper species in and around the Bay Islands will be seriously affected. The success of artisanal fishing methods and techniques used in Utila is extremely dependant on the surrounding weather conditions. Fishermen have had to adapt and become skilled in reading and understanding weather conditions in order to support their livelihood and earn a living. Constantly changing weather conditions not only alters the focus of catch but also causes changes to the distribution of fish stocks. Fishes change location during a storm in order to shelter from the harsh conditions and as a result is can take days for stocks to return to usual feeding and hunting grounds. The fluctuations in the results shown are as a result of these changing weather conditions which have caused fishermen to change techniques, constantly testing the conditions and altering techniques and locations accordingly. It must also be noted that although Diving was the predominate method of capture throughout the study, Grouper were not the main target of this method and were solely a by catch product of Conch and Lobster fishing. 4.2 Stomach Content Analysis The last available dietary study of a range of Grouper species at one time was conducted by J.E Randall in 1965 in the West indies, in which the stomach content of 212 different species were examined which included 9 members of the Epinephelus and Mycteroperca genera s. The study did not however include E.nigratus (Warsaw Grouper) preventing any dietary comparisons to be made. In comparing the two studies from 2008 and 1965 it can be seen that there are significant differences between the results. [Fig 26] A general impression is that in the subsequent 43 years there has been a large dietary shift from predominantly crustaceans such as crabs and shrimps to fishes. 53

50 It must be noted that samples sizes do vary significantly between the two studies however in some cases such as analysis of E.morio the sample size varied by only one specimen and this still resulted in a complete shift from predominantly crustaceans in 1965 to largely fishes in Location of the studies will have resulted in some differences between results, however the majority of species assessed both predator and prey species are found throughout the Caribbean, including the West Indies and Honduras. An increase in piscivorous prey consumption contradicts the general overfishing principle where a decrease in the abundance of piscivorous prey would be expected. However the range of prey species consumed are predominantly small reef fishes that are of little to none commercial interest, generally caught as by catch and either discarded or consumed by locals. Thus this finding supports the idea that a decrease in the abundance of large, top keystone predators as a result of intense fishing will result in an increase in the abundance of smaller reef prey species and thus leading to a greater number of available prey species relative to the decreasing number of grouper predators. A very small number of other studies looking at the diet of grouper species using stomach content analysis have been conducted including a study of the Dusky Grouper Epinephelus marginatus in

51 Figure 26: Dietary comparison between the results of this study 2008 and of J.E Randall s study from The results for E.nigratus are not available. 55

52 From the analysis of the gonads sampled it is difficult to draw any conclusions due to the small number of samples that were collected with gonads present. In the largest demographic collected M.venenosa, where there were 4 male, 10 female and 11 N/A samples this would equate to approximately a 1:2 male to female ratio, not including the samples with no gonads present. Generally this would indicate the status of the supporting reef to be healthy, supporting a good ratio of both male and female Groupers. However due to the lack of data this presumption cannot be concluded indefinitely and must remain as merely a positive indication. Results of the Observation dives raised an interesting issue, that although specimens of M.bonaci are being frequently observed in the Eastern waters of Utila and are common throughout the Bay Islands, they were not being landed at the time of the study. This is occurring as the fishermen of Utila tend to fish to the West of the island where there is a bank and drop off, compared to the east of the island where there is rival competition from more commercial fisheries including small fleets. 5. Conclusion This study has demonstrated a vital insight into the current status of fish abundance due to artisanal fishing within Utila and the Bay islands. Through using both catch assessment and stomach content analysis techniques, a complete picture has been created as to the species, sex ratio, abundance, size distribution of landed catch. It has been shown that the size of landed grouper species is significantly low, with the majority of groupers being caught before or at the time of sexual maturity and management actions need to be taken in order to ensure the continued survival of the species. Possible remedies such as returning juveniles and specimens bellow a certain length will not be of great effect with Groupers due to the depths at which some individuals are caught. Mortality through pressure changes is one of the most significant 56

53 threats to species such as E.nigratus who are pulled from the deep as by catch from Snapper trawlers [FAO Species Catalogue 1993] A possible method of ensuring the continued survival of the Serenade family is to target spawning aggregations. Spawning aggregations should be included in fisheries and conservation management plans, as well as during designation of marine protected areas. Although there is currently little effective management in place, there has been much progress in recent years by governments and conservation groups towards such goals. The primary aim of management is to reduce and control the amount of fishing so that aggregations remain stable over the long-term. In some cases, the removal of small numbers of fish might be sustainable in traditional fisheries but, in most cases, experience has shown clearly that fishing should probably be banned, either at specific times of the year, at key locations, or by some combination of measures. The study conducted was of a very small proportion and to fully gauge the scale of the problem a longer study over a period of at least 6 months to a year that encompassing the same methods is needed. It would be particularly interesting to conduct the study at the time of known spawning aggregations, in order to fully comprehend the scale of which specimens are caught at these specific times, as well as identifying if spawning season causes any specific dietary shifts within the different species and between different sexes. A study at the time of spawning aggregations would also help form an idea as to the age at which species reach maturity, a topic that is also under researched. Specific to the study conducted, if undertaken again there is a need for more assistance in regards with data and gut sample collection, due to the fact that fish were landed at both fisheries all in a similar time period, which hindered the amount of specimens that could be collected. In relation to the amount of guts collected this would be particularly important because specimens are gutted and cleaned immediately after landing. There is also a need to ensure similar sized data sets throughout the different species demographics in order to ensure viable and comparative data to analyse. 57

54 The cooperation, which at times was tested, of both the fishermen, garifuna and the fishery owners played a vital role in the relative success of this project. In order for any future management or conservation efforts to succeed, along with continued local fishery statistics, the continued positive social relationships between the community of the Cays, Utila and supporting ecological groups is vital, something that UCME is passionate about undertaking. 58

55 7. References Smith C, L Synopsis of biological data on groupers (Epinephelus and allied genera) of the western North Atlantic. FAO Fisher. Biol., Synopsis no. 23: vi + 61 pp., 19 figs. Heemstra, P. C. & Randall, J. E. (1993). FAO species catalogue. Vol. 16. Groupers of the world (Family Serranidae, Subfamily Epinephelinae). An annotated and illustrated catalogue of grouper, rockcod, hind, coral grouper and lyretail species known to date. FAO Fisheries Synopsis 125 Moe, M. A. Jr (1969). Biology of the red grouper (Epinephelus morio Valenciennes) from the eastern Gulf of Mexico. Professional Paper Series of the Marine Laboratory of Florida 10 NOAA Species of concern; Epinephelus nigritus (Warsaw Grouper).NOAA National Marine Fisheries Service Sulka, R, D 2001 Influence of habitat on grouper abundance in the Florida Keys, U.S.A. Journal of Fish Biology (2001) 58, Bannerot, S., Fox, W. W. Jr & Powers, J. E. (1987). Reproductive strategies and the management of snappers and groupers. In Tropical Snappers and Groupers :Biology and Fisheries Management (Polovina, J. J. & Ralston, S., eds), pp Bohnsack, J. A. (1982). Effects of piscivorous predator removal on coral reef fish community structure. In Gutshop 81: Fish Food Habits Studies (Cailliet, G. M. & Simenstad, C. A., eds), pp Chiappone, M., Sluka, R. & Sullivan Sealey, K. M. (2000). Groupers (Pisces: Serranidae) in fished and protected areas of the Florida Keys, Bahamas and northerncaribbean. Marine Ecology Progress Series 198, Goeden, G. B. 59

56 (1982). Intensive fishing and a keystone predator species: ingredients for community instability. Biological Conservation 22, Nagelkerken, W. P. (1981). Distribution of the groupers and snappers of the Netherland Antilles. In Proceedings of the Second International Coral Reef Symposium pp Manila: University of Philippines. Parrish, J. D. (1987). The trophic biology of snappers and groupers. In Tropical Snappers and Groupers: Biology and Fisheries Management (Polovina, J. J. & Ralston, S., eds), pp Sluka, R. & Sullivan, K. M. (1996). The influence of habitat on the size distribution of groupers in the upper Florida Keys. Environmental Biology of Fishes 47, Sluka, R., Chiappone, M., Sullivan, K. M., Potts, T. A., Levy, J. M., Schmitt, E. F. & Meester, G. (1998). Density, species and size distribution of groupers (Serranidae) in three habitats at Elbow Reef, Florida Keys. Bulletin of Marine Science 62, Colin. P, Sadovy. Y, Domeier.M (2003) Manual for the Study and Conservation of Reef Fish Spawning Aggregations, SCRFA Carter, J, Pryor V (1994) Aspects of the ecology and reproduction of Nassau grouper, Epinephelus striatus, off the coast of Belize, Central America. Proc. Gulf and Carib. Fish. Inst. 43: Colin, P. L. (1982). Aspects of the spawning of western Atlantic reef fishes. NOAA Tech. Mem.NMFS-SEFC 80: Sadovy, Y and P.L. Colin. (1995). Sexual development and sexuality in the Nassau grouper, Epinephelus striatus (Bloch) (Pisces: Serranidae). J. Fish Biol. 46: Sadovy, Y. and Eklund, A. 60

57 (1999). Synopsis of biological data on the Nassau grouper, Epinephelus striatus (Bloch, 1792), and the jewfish, E. itajara (Lichtenstein, 1822). U. S., Dep. Commer., NOAA Tech. Rep. NMFS 146; FAO Fisheries Synopsis 157, 65 p. Carlson. L, Fitzhugh. G, Plamer. C (2008) Regional size, age and growth differences of red grouper (Epinephelus morio) along the west coast of FloridaFisheries Research 91 (2008) Cummings, N (1996) Important aspects of the life history of the Yellowfin Grouper, Mycteroperca venenosa, with emphasis on populations in the Caribbean. Whaylen, L., C.V.Pattengill-Semmens, B.X.Semens, P.G. Bush and M.R. Boardman. (2004)Observations of a Nassau grouper, Epinephelus striatus, spawning aggregation site in Little Cayman, Cayman Islands, including multi-species spawning information. Environmental Biology of Fishes 70: , Thompson, R. and J.L. Munro, Aspects of the biology and ecology of Caribbean reef fishes: Serranidae (hinds and groupers).. J. Fish Biol. 12(2): Sierra, L.M., R. Claro, and O.A. Popova. (2001). Trophic biology of the marine fishes of Cuba. p In: R. Claro (ed.) Allison, E. H., and F. Ellis. (2001). The livelihood approach and management of small-scale fisheries. Marine Policy 25: Humann, P (1996). Reef fish identification. NewWorld Publications, Jacksonville, Florida. Roberts, C. M. (1997). Ecological advice for the global fisheries crisis.trends in Ecology & Evolution 12:

58 Appendix 1 Index of Scientific and Vernacular Names Scientific Name Abbreviation Common Name Local Name Mycteroperca Venenosa M.venenosa Yellowfin Grouper Rockfish Mycteroperca Tigris M.tigris Tiger Grouper Grupa Mycteroperca interstitialis M. interstitials Yellowmouth Grouper Dupper Grouper Epinephelus morio E. morio Red Grouper Mud Grouper Epinephelus guttatus E.guttatus Red Hind Jimmy Hind Epinephelus Striatus E.striatus Nassau Grouper Grupa Epinephelus nigritus E.nigratus Warsaw Grouper Congo Grouper 62

59 Appendix 2 Species Geographical distribution by major fishing area [FAO Species Catalogue V16] Species Mycteroperca Venenosa Mycteroperca tigris Mycteroperca interstitialis Epinephelus striatus Epinephelus nigritus Epinephelus morio Epinephelus guttatus Geographical Distribution by Major Fishing Areas

60 PLATE I (a) E.gutattus (b) E.striatus (c) M.veneosa 64

61 PLATE II (a) E.nigratus (b) E.morio (c) M.intertitilas 65

62 Plate III (a) M.tigris (b) Chromis cyaneus: M.veneosa (c) Sarda sarda: M.venenosa 66