Reproductive biology of the spiny lobster, <Emphasis Type="Italic">Panulirus Penicillatus</Emphasis>, in the southeastern coastal waters off Taiwan

The reproductive biology of spiny lobster, Panulirus penicillatus, was studied based on 2,068 lobsters, ranging from 34.28 to 131.60 mm carapace length (CL), sampled in Taitung coastal waters from September 2003 to December 2004. The overall sex ratio approximated 1:1 (χ² = 0.02, P > 0.05), but the monthly sex ratios in 2004 showed significant differences and males were predominant in sizes larger than 80 mm CL. Reproductive activity, assessed using histology, a gonadosomatic index and percentage of ovigerous females, indicated that the mature females could be found in every month and that the major spawning occurred from May to September. The presence of re-developing/re-ripe ovaries by month and size-specific spawning time suggest that larger mature females (>60 mm CL) spawn at least three times a year while smaller new mature females spawn at least once a year. For females, the estimated sizes at 50% physiological and functional maturity were (mean ± SE) 56.46 ± 0.56 mm CL and 66.63 ± 1.07 mm CL. The estimated sizes at functional maturity were between 72 and 74 mm CL for males. The number of eggs per spawning event (brood size, BS) was related to CL by the equation Y _BS = 2.4 × 10^-3CL^4.18 (r ² = 0.902, n = 12). Female lobsters with CL ranging from 60 to 80 mm made the greatest contributions to egg production because of their high brood size and active reproductive activity. A minimum legal size should be established for the fishery to protect egg production potential of lobster population in the southeastern coastal waters off Taiwan.     

Generalised linear modelling of fecundity at length in southern rock lobsters, <Emphasis Type="Italic">Jasus edwardsii</Emphasis>

Accurate fecundity estimates are central to population modelling of reproductive status and egg production in a fishery. Southern rock lobster (Jasus edwardsii) fisheries are managed with the consideration of performance measures based on the level of current egg production relative to the unfished stock. Egg production is a function of the size at the onset of maturity, the size structure of the stock, and the fecundity at length of lobsters. Fecundity at length of the Tasmania stock of J. edwardsii has not been reported previously and was estimated from seven sites around Tasmania. Data were analysed by classical linear regression and also generalised linear models (GLM) with gamma and Poisson distributions. GLM with a gamma distribution produced the best fit and did not require a correction factor to generate a model on the linear scale. Individual fecundity ranged from 43,918 to 660,156 and could be predicted from carapace length according to the equation F = −1.707 + 2.969 (log length). The coefficient of length approximated three, implying the fecundity at length relationship is cuboidal. Despite the spatial heterogeneity in reproductive parameters in this fishery, the inclusion of spatial information and egg development stage into the analysis only explained an additional 1% of the variance in fecundity. Thus, it appears valid to apply the relationship across the fishery without spatial separation.     

Long-term trends in invertebrate–habitat relationships under protected and fished conditions

Few studies examine the long-term effects of changing predator size and abundance on the habitat associations of resident organisms despite that this knowledge is critical to understand the ecosystem effects of fishing. Marine reserves offer the opportunity to determine ecosystem-level effects of manipulated predator densities, while parallel monitoring of adjacent fished areas allows separating these effects from regional-scale change. Relationships between two measures of benthic habitat structure (reef architecture and topographic complexity) and key invertebrate species were followed over 17 years at fished and protected subtidal rocky reefs associated with two southern Australian marine reserves. Two commercially harvested species, the southern rock lobster (Jasus edwardsii) and blacklip abalone (Haliotis rubra) were initially weakly associated with habitat structure across all fished and protected sites. The strength of association with habitat for both species increased markedly at protected sites 2 years after marine reserve declaration, and then gradually weakened over subsequent years. The increasing size of rock lobster within reserves apparently reduced their dependency on reef shelters as refuges from predation. Rising predation by fish and rock lobster in the reserves corresponded with weakening invertebrate–habitat relationships for H. rubra and sea urchins (Heliocidaris erythrogramma). These results emphasise that animal–habitat relationships are not necessarily stable through time and highlight the value of marine reserves as reference sites. Our work shows that fishery closures to enhance populations of commercially important and keystone species should be in areas with a range of habitat features to accommodate shifting ecological requirements with ontogenesis.     

Importance of rock lobster size–structure for trophic interactions: choice of soft-sediment bivalve prey

Ecologists are becoming increasingly interested in how variation in predator demographics influences prey communities. In northeastern New Zealand, the contrasting populations of previously exploited predators in highly protected marine reserves and fished areas have been used to investigate the effects of predation in soft-sediment habitats. However, these experiments have been unable to separate the role of predator size from that of density. This study provides evidence to support the model that foraging by different sizes of the rock lobster Jasus edwardsii affects soft-sediment bivalve populations in different ways. Feeding trials were conducted to investigate whether rock lobsters of different sizes vary in their choice of taxa and size of their bivalve prey. Trials with two morphologically similar species, Dosinia subrosea and Dosinia anus, indicated that lobsters of all sizes choose D. subrosea more frequently than the heavier shelled D. anus. Further results indicated that both large (>130 mm carapace length (CL)) and small (<100 mm CL) lobsters are capable of preying on a wide size range of D. subrosea (20–60 mm). However, small lobsters more frequently chose smaller shells (<30 mm) and large lobsters more frequently chose larger shells (>40 mm). Patterns in the abundance and size class distributions of these two bivalve species at protected and fished sites supported the feeding choices observed in the laboratory. These results suggest that populations of rock lobsters with large individuals inside reserves are capable of controlling the demography of bivalve populations in adjacent soft-sediment systems.     

Shelter preference in captive juveniles of European spiny lobster <Emphasis Type="Italic">Palinurus elephas</Emphasis> (Fabricius, 1787)

Physical shelter features (e.g. shape, size and substrate slope) were tested in the laboratory to evaluate the preferences of juveniles of European spiny lobster, Palinurus elephas. Tethering experiments to assess whether substrate slope affects the vulnerability of juveniles to predation were also performed. Our results showed that: (1) semi-circular dens were significantly preferred over square and circular shapes; (2) when not disturbed by a predator, lobsters sheltered in holes with a diameter closely related to their own size, while in the presence of a potential predator lobsters showed no significant preference for a particular shelter size; (3) lobsters significantly preferred dens excavated on sub-vertical (35°) substrates over those excavated on vertical ones (90°); (4) individual lobsters tethered on vertical substrates were subject to greater predation activity than those tethered on horizontal structures. In conclusion, the present study contributes to the understanding of how physical properties of shelters affect the choice of P. elephas juveniles, enhancing their protection and survival rate.     

Fecundity of red coral <Emphasis Type="Italic">Corallium rubrum</Emphasis> (L.) populations inhabiting in contrasting environmental conditions in the NW Mediterranean

In this study, we examined the variability and potential patterns of fecundity in the precious Mediterranean red coral Corallium rubrum (L. 1758). A total of 12 populations were selected from the NW Mediterranean Sea. We used a hierarchical sampling design to explore fecundity patterns associated with different environmental conditions found in different cave zones (entrance vs. interior), depths (15–22 vs. 39–42 m), and geographic locations (Côte Bleue vs. Calanques). Overall, 240 apical tips from colonies (10 male + 10 female colonies per population) were analyzed. Fecundity ranged between 1.0 ± 0.7 and 3.2 ± 2.3 mature gonads per polyp in female colonies and between 2.5 ± 1.6 and 6.9 ± 2.5 mature gonads per polyp in male colonies. The fecundity of red coral varied significantly for populations dwelling in different cave zones and geographic areas but not for the examined depths. Our results contribute to the knowledge of red coral fecundity in populations not yet studied in the NW Mediterranean and elucidate significant variability in fecundity within different environmental conditions. The information on coral fecundity can contribute to the development of management and conservation plans for red coral populations.     

Shelter selection of the spiny lobster <Emphasis Type="Italic">Palinurus elephas</Emphasis> under different levels of <Emphasis Type="Italic">Octopus vulgaris</Emphasis> predation threat

The skill of recognizing and reacting to predators is often based on a learned component. Few studies have examined the role of learning in spiny lobster anti-predator behavior. We investigated whether European spiny lobster (Palinurus elephas) shelter selection is influenced by olfactory stimuli released by one of the most common lobster predators, the common octopus (Octopus vulgaris), and whether the behavioral response to octopus chemical stimuli is innate or influenced by experience. In experimental arenas, we conditioned wild-caught lobsters with three levels of predation threat: no threat, with no predator–prey interaction; medium threat, with odor and visual predator cues only; high threat, active predation risk. We subsequently tested the shelter choice of the conditioned lobster under different experimental conditions: (1) shelter plus seawater; (2) shelter plus seawater plus chemical octopus cue. Our results showed significant differences in mean shelter occupancy with conditioning level. We conclude that P. elephas individuals use chemosensory systems in predator-avoidance mechanisms. Moreover, lobsters subject to a training period of high-level predation threat were able to learn the octopus chemical stimuli and treat its odor as a cue related to predation risk. The findings relative to the spiny lobster learning abilities could be an important tool for future management of lobster populations, e.g., by re-introduction of reared juveniles, which have not yet experienced predation.     

Effects of sex change on the implications of marine reserves for fisheries

Marine reserves have become widely used in biodiversity conservation and are increasingly proposed as fisheries management tools. Previous modeling studies have found that reserves may increase or decrease yields, depending on local environmental conditions and on the specific life-history traits of the fishery species. Sex-changing (female-to-male) fish are targets of some of the most important commercial and recreational fisheries in the world. The potential for disproportionate removal of the larger, older sex of such species requires new theory to facilitate our understanding of how reserves will affect the yields of surrounding fisheries, relative to fishes with separate sexes. We investigated this question by modeling the effects of marine reserves on a non-sex-changing and a sex-changing population. We used demographic parameter estimates for the common coral trout as a baseline, and we conducted extensive sensitivity analyses to determine how sustainable yields of sex-changing species are likely to be affected by reserves across a broad range of life-history parameters. Our findings indicate that fisheries for sex-changing species are unlikely to receive the same yield-enhancing benefit that non-sex-changing fisheries enjoy from marine reserves, and that often reserves tend to reduce sustainable yields for a given overall population size. Specifically, the increased egg production and high fertilization success within reserves is more than offset by the reduced egg production and fertilization success in the fished areas, relative to a system in which fishing mortality is distributed more evenly over the entire system. A key reason for this appears to be that fertilization success is reduced, on average, when males are unevenly distributed among subpopulations, as is the case when reserves are present. These findings suggests that, for sex-changing populations, reserves are more suited to rebuilding overfished populations and sustaining fishery viability, rather than enhancing fishery yields. These results are robust over a range of sex-change regimes, stock-recruitment relationships, adult mortality rates, individual growth strategies, and fertilization-success functions. Our findings highlight the importance of considering the different contributions of males and females to population growth and fishery yields when evaluating the efficacy of marine reserves for enhancement of fished species.     

Latitudinal variation in the reproductive biology of the burrowing ghost shrimp Callianassa filholi (Decapoda: Thalassinidea)

Population structure and reproductive ecology of the burrowing ghost shrimp Callianassa filholi Milne-Edwards, 1878 were studied in populations along a latitudinal gradient throughout New Zealand during the breeding season. Size-frequency distributions revealed unimodal populations, with predominantly sexually mature shrimp. All populations showed an unbiased sex-ratio, and there appeared to be no significant difference in size (carapace length, CL) between sexes. At the same time, CL and size at maturity differed significantly between populations; however, a general increase in sizes from north to south was not consistent throughout the latitudinal range studied. The timing of the breeding cycle differed significantly between populations, and breeding started earlier in southern populations. Number of embryos (fecundity) increased linearly with female CL at each location, but rates differed significantly between populations. Embryo size was not related to number of embryos, and the former increased significantly with latitude. With the exception of embryo size, observed differences in body size/size at maturity and reproductive timing between C. filholi populations are thought to be determined by food availability rather than temperature. Thus, further study is suggested on these aspects of thalassinid reproductive biology. Received: 17 June 1999 / Accepted: 8 January 2000     

Temperate marine reserves enhance targeted but not untargeted fishes in multiple no-take MPAs.

Although many papers report the effects of no-take marine protected areas (MPAs or reserves), scientifically rigorous empirical studies are rare, particularly for temperate reef fishes. We evaluated the responses of fish populations to protection from fishing in reserves by comparing densities and sizes inside and outside of five no-take reserves in southern California, USA. Our results are robust because we compared responses across multiple rocky-reef reserves in two different years and controlled for possible site differences by (a) ensuring that habitat characteristics were the same inside and outside reserves, and (b) sampling species that are not targeted, which would not be expected to have a direct response to fishing. We compared fish density and size and calculated biomass and egg production across all five sites. Fishes targeted by recreational and/or commercial fisheries consistently exhibited increases in mean density (150%), size (30%), biomass (440%), and egg production (730%) inside reserves. Reserve effects were greatest for legal-sized targeted fishes: significantly greater densities were found exclusively inside reserves for targeted species (580%), the largest size classes existed only inside reserves, and mean biomass was 1000% higher. These responses were unlikely to have been caused by habitat differences because there were no significant differences in habitat characteristics between reserve and control locations. Densities of non-targeted species did not differ between reserve and non-reserve locations, further supporting the conclusions that differences in targeted species between reserve and control locations were due to harvesting rather than site-specific effects. Although MPAs cannot replace traditional fisheries management, the concentration of increased biomass and egg production is a unique MPA benefit that serves both reserves and fisheries. Scientifically rigorous studies that include multiple reserves, such as this study, are needed to inform management and policy decisions.     

Maturity,fecundity, and reproductive cycle of the spotted ratfish, <Emphasis Type="Italic">Hydrolagus colliei</Emphasis>

Size at maturity, fecundity, and reproductive periodicity were estimated for the spotted ratfish, Hydrolagus colliei (Lay and Bennett, 1839), off the coast of California, Oregon, and Washington. Maximum body size and size at median maturity were greater for females than males. Skeletal muscle concentrations of the steroid hormones testosterone (T) and estradiol (E₂) predicted similar, but slightly smaller sizes at maturity than the morphological criterion. Stage of maturity for males was estimated identically using internal organs or external secondary sexual characters, thus allowing non-lethal maturity assessments. Size at median maturity was greater north of Point Conception for females, and north of Cape Mendocino for males. Peak parturition occurred from May to October, with increased concentrations of E₂ in skeletal muscle of females correlating with ovarian recrudescence during November to February. No significant seasonal trends in female T were apparent, but mean female 11-ketotestosterone (11KT) was 300% greater in April than any other month during the parturition season. There was a marginal evidence for increased number and size of ova with maternal size. Extrapolation of the hypothesized 6 to 8-month egg-laying season to observed mean parturition rates of captive specimens yielded an estimated annual fecundity of 19.5–28.9 egg cases. Differences in fecundity among higher taxonomic classifications of chondrichthyans were detected with chimaeriform fishes more fecund than lamniform, myliobatiform, squaliform, and rhinobatiform fishes, and less fecund than rajiform fishes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Changes in body size, abundance, and energy allocation in rockfish assemblages of the northeast Pacific.

Fish body size, a key driver of many aspects of fish population biology and ecology, is affected by fisheries that deplete the largest individuals. Rockfish (genus Sebastes) are a diverse group that has been heavily fished on the U.S. West Coast in recent decades. We examined trawl survey data from 1980 to 2001 to determine spatial and temporal trends in body size and density of 16 shelf rockfish species, including six that are considered overfished. Mean individual mass and maximum observed mass declined in the majority of species in one or more zoogeographic regions between central California and Washington. Density changes were far more variable in time and space, but in all regions, density declines were most often associated with large-bodied rockfish. We next estimated the impact of size and density changes on energy consumption and fecundity in a five-species rockfish assemblage that includes bocaccio (S. paucispinis), a large-bodied, overfished species. Indexes of both consumption and fecundity by the assemblage increased in the southern portion of the study area between 1980 and 2001 but decreased in the northern portion. Allocation of energy and reproductive potential within the assemblage shifted dramatically: relative to bocaccio, total energy consumption and fecundity indexes for the other four species increased by orders of magnitude from 1980 to 2001. These changes in community structure may affect the ability of bocaccio and other large rockfish species to recover from overfishing, especially in light of long-term declines in zooplankton production that may also be affecting rockfish size and production. Addressing these issues may require a regional, multispecies management approach.     

Defining ecologically relevant scales for spatial protection with long‐term data on an endangered seabird and local prey availability

Human activities are important drivers of marine ecosystem functioning. However, separating the synergistic effects of fishing and environmental variability on the prey base of nontarget predators is difficult, often because prey availability estimates on appropriate scales are lacking. Understanding how prey abundance at different spatial scales links to population change can help integrate the needs of nontarget predators into fisheries management by defining ecologically relevant areas for spatial protection. We investigated the local population response (number of breeders) of the Bank Cormorant (Phalacrocorax neglectus), a range‐restricted endangered seabird, to the availability of its prey, the heavily fished west coast rock lobster (Jasus lalandii). Using Bayesian state‐space modeled cormorant counts at 3 colonies, 22 years of fisheries‐independent data on local lobster abundance, and generalized additive modeling, we determined the spatial scale pertinent to these relationships in areas with different lobster availability. Cormorant numbers responded positively to lobster availability in the regions with intermediate and high abundance but not where regime shifts and fishing pressure had depleted lobster stocks. The relationships were strongest when lobsters 20–30 km offshore of the colony were considered, a distance greater than the Bank Cormorant's foraging range when breeding, and may have been influenced by prey availability for nonbreeding birds, prey switching, or prey ecology. Our results highlight the importance of considering the scale of ecological relationships in marine spatial planning and suggest that designing spatial protection around focal species can benefit marine predators across their full life cycle. We propose the precautionary implementation of small‐scale marine protected areas, followed by robust assessment and adaptive‐management, to confirm population‐level benefits for the cormorants, their prey, and the wider ecosystem, without negative impacts on local fisheries.     

Seasonal,diel, and tidal movements of green jobfish (<Emphasis Type="Italic">Aprion virescens</Emphasis>, Lutjanidae) at remote Hawaiian atolls: implications for marine protected area design

Empirical data quantifying the long-term movement patterns of coral reef top predators are needed in order to design marine protected areas (MPAs) that will provide these fishes with effective, long-term protection. Acoustic telemetry was used to quantify the movements of a large coral reef top predator (Aprion virescens, Lutjanidae; Hawaiian name ‘uku’) at five atolls in the Northwestern Hawaiian Islands Marine National Monument (NWHIMNM) from May 2005 to September 2006. The study atolls were located between 23.8°N, 166.2°W and 28.5°N, 178.3°W, and were separated from their nearest receiver-equipped neighbor by distances ranging from 100 to 478 km. No inter-atoll movements by uku were detected but individuals were seasonally site-attached to core activity areas of up to 12 km in length, and ranged up to 19 km across atolls. Within their core areas, tagged uku exhibited diel and tidal habitat shifts, with the latter resulting in round trips of up to 24 km in 24 h. Seasonal uku migrations resulted in extended winter (October–April) absences from summer (May–September) core activity areas and may be linked to summer spawning. Large MPAs (i.e., entire islands, atolls or banks) would probably be required for full protection of resident populations of adult uku, but such ‘island-scale’ MPAs will not benefit fisheries unless there is significant larval supply from MPAs to neighboring fished areas, or adult emigration over time scales exceeding the 16-month monitoring period of this study. A mixed management strategy of combining smaller MPAs with conventional measures (e.g., minimum size limits, catch, and effort restrictions) may be the best approach for sustaining uku fisheries. However, this would still require relatively large MPAs (12 km in length) to contain uku short-term (diel and tidal) movements, and seasonal migrations would still take uku beyond the boundaries of MPAs of this size. These fluxes across MPA boundaries could supply fish to fisheries but, if high exploitation rates exist, fishing could eliminate key MPA benefits such as increased numbers of large, highly fecund individuals. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Ovarian allometry and the use of the gonosomatic index: a case study in the Mediterranean sardine,<Emphasis Type="Italic"> Sardina pilchardus</Emphasis>

The gonosomatic or gonadosomatic index [GSI=(ovary weight/fish weight)×100] has been widely used in fisheries science and experimental reproductive studies as a simple, low-cost measure of reproductive condition. However, its properties have not been fully evaluated, and several pitfalls, such as size-dependence and changes in ovarian allometry, may invalidate its use. In the present study, we examined ovarian allometry and the appropriateness of GSI for assessing ovarian activity in the Mediterranean sardine Sardina pilchardus. The analysis was based on a large sample of histologically scored females collected over an annual cycle in the eastern Mediterranean (Aegean and Ionian Seas). First, we examined GSI dependence on fish size by comparing ovary weight–on–fish weight relationships in different stages of oocyte development. The effects of recent spawning (incidence of postovulatory follicles) and intensity of follicular atresia were also addressed. In a subsequent step of the analysis, we applied generalized linear models (GLMs) to analyze the relationship between GSI and histological stage, taking into account the parallel effects of additional factors related to geographical region, month of capture, fish length and energetic reserves (fat stage, hepatosomatic index—HSI). Ovarian growth was isometric in all stages of oocyte development and states of atresia, but altered to positive allometric at the stage of oocyte hydration. Oocyte growth and intensity of atresia significantly affected GSI. Fish length, geographical region, month of capture, fat stage and HSI did not substantially affect GSI, further strengthening the appropriateness of the index for the Mediterranean sardine. Finally, we provide first evidence, based mainly on available (but yet limited) published information for other fish species, that: (1) the pattern of ovarian allometry may not be altered by fecundity variations and (2) the pattern of ovarian allometry may reflect the pattern of oocyte growth (i.e. isometric vs. allometric ovarian growth could reflect group-synchronous vs. -asynchronous oocyte development). Alternatively, the pattern of ovarian allometry could reflect the presence or absence of size dependency in the relative fecundity (eggs per gram of body weight) and/or egg size. The isometric ovarian growth in the Mediterranean sardine could be attributed to the lack of such size-dependent effects.Communicated by O. Kinne, Oldendorf/Luhe     

Latitudinal variation in aspects of the biology of Cyclothone braueri and C. microdon (Pisces: Gonostomatidae) in the eastern North Atlantic Ocean

Samples from a series of RMT-8 tows along 20°W in spring and autumn of various years were used to study the variability in aspects of the breeding biology of two species of Cyclothone: C. braueri and C. microdon in the eastern North Atlantic Ocean. Variables compared within each species included length-frequency distribution, maximum size, size at maturity, sex ratio, egg size and fecundity. Populations of both species at lower latitudes were generally smaller, reached maturity at a smaller size, and probably spawned earlier in the year and over a longer period than populations at higher latitudes. In both species, fecundity was highest at 40°N in the spring. The results suggested that C. microdon may not spawn at the northern extent of its range.     

A Comparison of Linear Demographic Models and Fraction of Lifetime Egg Production for Assessing Sustainability in Sharks

Conventional methods for management of data‐rich fisheries maintain sustainable populations by assuring that lifetime reproduction is adequate for individuals to replace themselves and accounting for density‐dependent recruitment. Fishing is not allowed to reduce relative lifetime reproduction, the fraction of current egg production relative to unfished egg production (FLEP), below a sustainable level. Because most shark fisheries are data poor, other representations of persistence status have been used, including linear demographic models, which incorporate life‐history characteristics in age‐structured models with no density dependence. We tested how well measures of sustainability from 3 linear demographic methods (rebound potential, stochastic growth rate, and potential population increase) reflect actual population persistence by comparing values of these measures with FLEP for 26 shark species. We also calculated the value of fishing mortality (F) that would allow all 26 species to maintain an accepted precautionary threshold for sharks of FLEP = 60%, expressing F as a fraction of natural mortality (M). Values of stochastic growth rate and potential population growth did not covary in rank order with FLEP (p = 0.057 and p = 0.077, respectively) and neither was significantly correlated with FLEP. Ordinal ranking of rebound potential positively covaried with FLEP (p = 0.00013), but the relative rankings of some species were substantially out of order. Adopting a sustainable limit of F = 0.16M would maintain all 26 species above the precautionary minimum value of FLEP (60%). We concluded that shark‐fishery and conservation policies should rely on calculation of replacement (i.e., FLEP), and that sharks should be fished at a precautionary level that would protect all stocks (i.e., F< 0.16M). Comparación entre Modelos Demográficos Lineales y la Fracción de Producción de Huevos a lo Largo de la Vida para Estudiar la Sustentabilidad en Tiburones Resumen     

Hidden demographic impacts of fishing and environmental drivers of fecundity in a sea turtle population

Fisheries bycatch is a critical threat to sea turtle populations worldwide, particularly because turtles are vulnerable to multiple gear types. The Canary Current is an intensely fished region, yet there has been no demographic assessment integrating bycatch and population management information of the globally significant Cabo Verde loggerhead turtle (Caretta caretta) population. Using Boa Vista island (Eastern Cabo Verde) subpopulation data from capture–recapture and nest monitoring (2013–2019), we evaluated population viability and estimated regional bycatch rates (2016–2020) in longline, trawl, purse-seine, and artisanal fisheries. We further evaluated current nesting trends in the context of bycatch estimates, existing hatchery conservation measures, and environmental (net primary productivity) variability in turtle foraging grounds. We projected that current bycatch mortality rates would lead to the near extinction of the Boa Vista subpopulation. Bycatch reduction in longline fisheries and all fisheries combined would increase finite population growth rate by 1.76% and 1.95%, respectively. Hatchery conservation increased hatchling production and reduced extinction risk, but alone it could not achieve population growth. Short-term increases in nest counts (2013–2021), putatively driven by temporary increases in net primary productivity, may be masking ongoing long-term population declines. When fecundity was linked to net primary productivity, our hindcast models simultaneously predicted these opposing long-term and short-term trends. Consequently, our results showed conservation management must diversify from land-based management. The masking effect we found has broad-reaching implications for monitoring sea turtle populations worldwide, demonstrating the importance of directly estimating adult survival and that nest counts might inadequately reflect underlying population trends.     

The ecology of Indo-Pacific grouper (Serranidae) species and the effects of a small scale no take area on grouper assemblage,abundance and size frequency distribution

This paper used the case study of the Wakatobi Marine National Park, Indonesia to examine changes in the diversity, density and maturity of grouper species over a 5-year period following the establishment of a small-scale no-take area (NTA). This work was carried out to investigate whether “small” NTAs could be effective management strategies over a time scale that is relevant to local fishery communities and their perception of management success. Our research also documents the ecology of these species, information essential if we are to understand how management practises are to affect coral reef fish species. Designation of this “small NTA” increased the density of groupers by 30% over a 5-year period of protected status. After 5 years of protection, grouper populations within this NTA were more mature and double the density of those within the adjacent lightly fished sites and nearly five times those of a heavily fished site. During this time all other nearby fished sites underwent large declines in grouper density. The nearby lightly fished Kaledupa site decreased by up to 50% year⁻¹. Such drastic declines are considered the impact of the exponential development of ever efficient and unsustainable methods of fishing within the study region. This NTA was not of benefit to all grouper species; the reasons for which are not clear. Such questions require further detailed research about the life history, population and behavioural ecology of Indo-Pacific grouper species. Such information is critical for urgently needed fisheries management. The present study found that a small scale NTA of 500 m length was large enough to increase the population of top predatory fish. In conjunction with other socially acceptable small scale NTAs it could help maintain and increase important fish stocks over a larger area. The use of “small” NTAs within networks of reserves should become a useful tool in the management of the locally exploited coral reefs.