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postsettlement fishes study (Rakitin and Barbados Marine Reserve, did postsettlement fishes study (Rakitin and Barbados Marine Reserve, did

postsettlement fishes study (Rakitin and Barbados Marine Reserve, did - PDF document

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postsettlement fishes study (Rakitin and Barbados Marine Reserve, did - PPT Presentation

fishery reserve chain Fig north near in the Cays Land Fig 1B Our MFR by in densities consider physicaloceano mechanisms for such with respect regions 4 bean locations is relatively The spec ID: 349231

fishery reserve chain (Fig. north

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postsettlement fishes study (Rakitin and Barbados Marine Reserve, did provide conclusive allowed for fishes into fishermen and other In this and culturally was made central Bahamas The fished study sites central Bahamas located within fishery reserve, detailed maps arrows indicate dashed lines fishery reserve chain (Fig. north near in the Cays Land (Fig. 1B). Our MFR by in densities consider physical-oceano- mechanisms for such with respect regions; 4) bean locations. is relatively The species western Atlantic and southern Trinidad (Abbott, 1974). Several masses, each containing -400,000 eggs, sand during summer season (Robertson, Stoner and d and phytoplankton (Brownell, 1977; Davis slight (Barile and the larvae drift 1989; Campton and analysis 1993) suggest seagrass nursery into deeper water with reach sexual maturity, cease in shell flared shell lip 1985; Appeldoorn, (Berg, 1976) 1987). Fishing regulations (i.e. juvenile) queen any kind (Randall, 1964; Adams, 1970). region was severe overfishing and Olsen, 1994a), queen was considered commercially al., 1983) multiyear periods Cuba, and Despite closure in Florida (since 1985) Bermuda (since comprises more central Bahamas, Great Bahama Bank (Fig. sand and a steep beginning at, m depth. land (LSI) where fishing The hard-bottom sp. in many the habitat is large coral ridges with lacks beaches, and water LSI, small sandy beaches lie locations between Water exchange numerous passes separate the lands, creating most queen reproductive ac- shelf, where highest densities are rare Stoner and B and Discrete juvenile aggregations, with bank in the same general al., 1991; Great Bahama The Exuma and Sea 1958, extends km along km across full-time warden This investigation was park headquarters fishing regulations enforced. The km from park and were conducted in the Exuma Sound between March 1991 (Stoner and Schwarte, study. Annual surveys where fishing allowed, showed little interannual variation in population different years. 1991, maximum mean population size was population was m depth 1992) differed 1994. Given relative stability LSI could be most compelling evi- dence for size. For comparison, survey those used km along north and this area, snorkeler was small boat 6-m-wide field made along started near islands and Positioning System (GPS). This resulted direct observation and the entire area. test the depth distribution sites, depth-stratified were conducted Sound along Pond Cay were spaced transect, estimates depth intervals: m, and Within each diver carried a calibrated distance traveled. tance measured, divers swam any discernible isobaths. Thirty-six were made during this distance was (SD=6 m). Sampling deepest sampling tively small comparable with Stoner and Schwarte for which GPS) were boat. Computer- with nor- algorithms. Surface tour interval mean density surveys was determine total depth interval. examine age distribution and shell lip thickness were depth interval 213 individuals Although young terial faster adults and although shells erosion, shell relative indication age (Appeldoorn, with depth, shell length shell lip-thickness depth interval Several aspects fishery reserve Island. Estimates total abundance density surveys habitat and Habitat and Area Total 2.2 21.7 including shell juvenile queen the bank Exuma Sound. the data) and Quinn (1989). Prior analysis, variances heterogeneity with from LSI Stoner and Schwarte, 1994) and tables. Juvenile surveys juvenile queen the areal high densities (Stoner and in the divers were boundaries within density was 20.1 marked with determined with The potential measured with were plotted Absolute position was not critical aggregation sizes. Surface aggregations were determined with digitizing board. Surveys have been the adult juvenile surveys were concentrated island and Bahama Bank in the and Rat (Fig. 1C). Although most associated with these entire bank and the was searched. surrounding bank particular tidal nurseries in adjacent bank and juvenile aggregations was calculated bank area provides only abundance without sity within aggregations, our long experience juvenile aggregations in the have General observations 1991 surveys both sites. were conducted spawning season in the late-stage larvae. 15 July, 4 m isobath) 18 August) stage larvae day (Stoner in the made for was calculated meter (General Samples were preserved formalin-seawater mixture. Strombid veligers were with a al. (1993). The number veligers per tow were shell length. The veligers metamorphically competent density and ANOVA of depth intervals revealed significant differences both between deepest interval m) was analysis because in the not significant each depth mean den- This value was times higher than the area near was significantly higher depth intervals deep (Table conchha) and beach locations surveyed. density within depth intervals was high and apparently related example, density and E density was in transect The density the bank Pond Cay times higher in the Seventy-four percent were within was also evident was 45.6% and bank. were only 6,816 adults in and this a rela- tively small portion showed differences shell length bank and depth interval all cases) (P=0.14). Adult conch from (Fig. 2). The m and m and and mml was found). shell length m and m intervals. was observed tervals, with with 188 (SD-20 mm, son showed significant differences depth interval (Fig. 2). in the area had thickness in depth interval cases) because those shell lips. adults had shell lips thickness values the three depth inter- inter- Shelf 2.5-5 m 20 10 0 L a, Shelf 15-20 m 30 i Shelf 20-25 m 140 150 160 200 210 220 230 240 270 280 shell length Exuma Sound in the and in Each value represents a range mm). Mean shell sample size in parentheses given for 15 m had lip thickness mm. Beyond 15 m lip thick- conch from sound was 24 mm in frequency shell lip thick- bank and in all cases) except for (Fig. 3). water (bank, and deeper water. in the (mean )in the (Fig. 4). Highest density sound (33.3 the standard depth interval densities were 5.1 juveniles/ Sound were shell lip thickness bank and fishery reserve LSI (points). given for each distribution. 32 37 Great Bahama area, interannual was high, in the in the Bay Cay field (Table 2). a large average surface 6 yr juvenile aggregations covered 3.84% mean value were consistently 3). Densities magnitude higher, reaching in July notable in 1993 when 184 times 15-20 20-25 area near Schwarte, 1994) fishery reserve than the tion (Table Late-stage larvae (2900 ym SL) were always in the higher densities The highest 1.9 late-stage were also earlier investigations other studies made difficult data in adult and suggests high regional densities, ranging juvenile queen fields, one and the originating between Children’s Bay (see Fig. occupied by juvenile aggregations. Larval densities fishery reserve area near offshore for from Student’s variances when 0.63 rt0.44 5.94 11.44 Fishery Bulletin fishery reserve and in area near Island. Samples are the Marine fishery reserve Fished Area 19.7 k24.9 1.25 k1.07 0.740 k0.348 Fished Area 0.646 k0.874 0.093 ir0.134 0.042 C0.060 values in each depth were always Bermuda, Florida, Islands. Densities were comparable before 1984 Cruz, Cuba, other studies value was our fished area near lands, adult density was maximum (17.1 m (Friedlander densities (18.3 in our fished the literature The highest single density highest densities fishery reserve was subsequently de- illegal fishing Posada, 1994), lation density throughout 1994a). Densities in the (Hesse, 1979), Laughlin, 1984), (Torres Rosado, Islands (Friedlander Bahamas (Stoner number in LSI can free-diving fishermen, differences between partly to fishing, although �30 veligers/lO these studies. in 1988 (Posada and Appeldoorn, 1994), highest value 0.68 veligers/lO Rodriquezl). The single value recorded Exuma Sound was 1994, with all other press; Stoner and Mehta, Exuma Cays, directly associated with abundance fishery reserve reported throughout decreasing latitude. Great Bahama Bank Islands, United Islands, United Roques, Venezuela Torres Rosado Distribution, abundance, shallow-water fishery resources Baharna Banks. shell length were both density and they together in were density differences, bank waters. two field that an time se- and after 1986; Osenberg 1994; Underwood, 1994). Unfortunately Exuma Cays Land and Sea collected before fishing closure. This is associated with (see Roberts should use both time answers regarding when stocks Adult queen two locations (Torres Rosado, and data Cays sites. long-term conservation ing waters. such questions and larval import and export. abundance make analysis unique insight into in the such mechanisms Site-specific differences shell size in explain- shelf environment Exuma Sound a larger Great Bahama shell size fishing pressure, Stoner primary source deep-water reproductive mostly young most were deeper shelf environment. the bank in distribution virtually LSI (i.e. small shelf where were able deeper shelf ing. Therefore, although sound population adjacent Exuma Sound shelf. result in artificial selection shell lip thickness, in the The reverse was evident was higher deep-water spawning population. conch only spawning stock. in general, virtually all juveniles and first- Exuma Cays water and all free-diving fisher- after reaching adulthood. Protection migratory pathway and larvae in addition fect differences juvenile aggre- magnitude larger in the relatively small in all juvenile aggregations in relatively high densities larvae arriving late-stage larvae times higher area. In was approximately The supply in the in larval and transport. Virtually nothing the sur- is little In terms Exuma Cays shelf is a station the current km/day (Hickey2). late-stage queen high densities and adults in the also highly (Stoner, unpubl. high density reduced fishing Oceanography, Univ. Washing- surrounding current probably not spawning stocks located reserve. With a northwest Exuma Cays conch. However, port distances plumes. Because reserves must metapopulation context al., 1995). a significant in the Exuma Sound. were mea- sured in increased since Exuma Cays Land larval transport in this and fishery reserves. Although especially high. Cays Land a large reproductive stock where physi- export them fishing grounds. larvae, a oceanographic conditions dispersal range fishery reserves can indeed enhance fishery populations larvae, although incorporate design gal prohibition numerous tidal Fisheries, Ministry culture, Trade, those individuals water constitute unfished deep-water reproduc- tive stock, is vulnerable, tidal inlets, ductive grounds valuable. Reserve designs consider ontogenetic the target import, export, metapopulation dynamics optimize fishery ben- marine vertebrate and Mansfield, E. Schwarte, and and other Dill for with computer graphics; drafting maps; Bahamas National Exuma Cays anonymous reviewers manuscript. Funding National Undersea Research Pro- Literature cited Island, Grenadines, Trop. Sci. 12279-288. Crecimiento, varaciones in adult B. Rodriguez and mariculture, in the and its implications for management regulations. (eds.), Queen p 145-157. Strombus gigas, Mar. Biol. Strombus gigas, Caribb. Fish. Krieger, and Proc. Gulf (Strombus gigas) Marine invertebrate ment and for reef Tech. Memo. Strombus gigas, Bull. Mar. Sci. 27:668-680. among populations in the issues relevant marine harvest reef fishes. Dempsey, and (Strombus gigas) predation studies hatchery-reared juve- River Canyon, Proc. Gulf A comparison Ecol. Monogr. to coastal fisheries Sci. 50:2029-2042. temporal variations Rodriguez (eds.), and migration Strombus gigas, Mar. Sci. mariculture and preliminary results. Man, A., marine reserves recruitment to reef fisher- Strombus gigas. Ecology 76:981-994. larval dispersal, Strombus gigas, Abu-Saba, and environmental impacts: ity, effect Ecol. Appl. 4:16-30. small Caribbean in the Rodriguez (eds.), Fundacion Cien- Mar. Sci. 14:246-295. Proc. Malacol. SOC. London reef fishes Strombus gigas. Rodriguez, B., Revision hisMrica pesqueria del botuto B. Rodriguez marine reserves on fisheries: Wellington, New Environmental impact Ecology 67:929-940. press, a. Central Bahamas. Bull. Mar. Sci. Central Bahamas. Bull. Mar. Larval supply to queen nurseries: relation- population size Large-scale distribution (eds.), Queen Fundacion Cienti- Bull. Mar. Sci. Aggregation dynamics juvenile queen conch: popu- mortality, growth, Biol. 116:571-582. Bull. Mar. reproductive stocks probable sources. Torres Rosado, two mesogastropods, Rico. M.S. On beyond population dynamics, Queen or pink invertebrate red book, p. Hepp, and Preliminary studies set aside areas throughout population decreases a fished area and (m) Great Bahama depth inter- set aside areas throughout population decreases a fished area and (m) Great Bahama depth inter- in the mean adult density was times. Shell length measurements indicated water, whereas those in the from free-diving sparsely distributed area, and higher. Because northwest, late-stage spawned outside high densities are the in the area, protection from fishing. Although persed from reserve is uncertain, high numbers positive effect northern Exuma Sound. Designs import, export, metapopulation dynamics will op- timize fishery benefits marine vertebrate Fishery Bulletin fishery reserve Caribbean Marine Vero Beach, Present address: National Marine Fisheries Service, Caribbean Marine Vero Beach, coastline, reef, cally significant marine fishery reserves selected species. Bohnsack (1990) fishery reserves including benefits such undisturbed critical habi- provision for a larval 1991; Dugan 1992) have yielded evidence increase within reserves, there are also Roberts and Polunin, Roberts, 1993). planktonic larvae; therefore, in fishery yields surrounding waters, scientists, managers, 1993), although population dynamics al., 1995). Similarly, postsettlement fishes study (Rakitin and fishery reserve chain (Fig. north near in the Cays Land (Fig. 1B). Our MFR by in densities consider physical-oceano- mechanisms for such with respect regions; 4) km across full-time warden This investigation was park headquarters fishing regulations enforced. The km from park and were conducted fishery reserve Island. Estimates total abundance density surveys habitat and particular tidal nurseries in adjacent bank and juvenile aggregations was calculated bank area provides only abundance without sity within aggregations, our long experience juvenile aggregations in the have General observations 1991 surveys both sites. showed differences shell length bank and depth interval all cases) (P=0.14). Adult conch from (Fig. 2). The sound (33.3 the standard depth interval densities were 5.1 juveniles/ Sound were fishery reserve than the tion (Table Late-stage larvae (2900 ym SL) were always in the Fishery Bulletin fishery reserve and in area near Island. Samples are the fishery reserve reported throughout decreasing latitude. Great Bahama Bank and larval import and export. abundance make analysis unique insight into in the such mechanisms Site-specific differences shell size in explain- shelf environment Exuma Sound surrounding current probably not spawning stocks located reserve. With a northwest Exuma Cays conch. However, port distances plumes. Because Strombus gigas, Mar. Biol. Strombus gigas, Caribb. Fish. Krieger, and Proc. Gulf Larval supply to queen nurseries: relation- population size