Fisheries Exploitation Research Articles

First detailed description of follicle development in a chimaeroid, the American elephant fish Callorhinchus callorhynchus

Chimaerods represent an enigmatic lineage of cartilaginous fishes and the least studied group within Chondrichthyans. They have a widespread global distribution with a high degree of endemism. In addition, this group has been considered among the least threatened species of Chondrichthyans, but also the most data-deficient group, with biological information lacking for most species. This study represents the first microanatomical, histological, and ultrastructural description of the different stages of folliculogenesis in Callorhinchus callorhynchus, and the first ultrastructural study about this topic within chimaeroids. Specimens of different maturity stages were collected from landings of the commercial fleet operating in San Matías Gulf, Argentina. Folliculogenesis shows some differences compared to other elasmobranchs. Oogonia were present in immature and mature females. Atretic follicles of different sizes were present in mature female ovaries. There is a significant difference between the macroscopic (∼10 mm) and microscopic (∼ 2 mm) follicular size at the beginning of vitellogenesis. There is no evidence of an epigonal organ. The results are discussed in a physiological and reproductive context. This study provides valuable information that will contribute to the understanding of the reproductive biology of the chimaeroids species and its potential for fishery exploitation recovery.

Overview of small reservoirs of the south of Ukraine from the aspect of fisheries exploitation

Overview of small reservoirs of the south of Ukraine from the aspect of fisheries exploitation

Effects of fishing on the trophic structure of carnivorous fish assemblages from shallow rocky bottoms of the Mediterranean Sea and the temperate Atlantic Ocean

Abstract Here, we assess whether fishery exploitation affects the trophic structure of carnivorous fish. We censused fish and analysed the stable isotope ratios of C and N of species targeted by fishermen in areas open to fishing and marine protected areas (MPAs) in the Mediterranean Sea and the north-eastern Atlantic Ocean. Results demonstrated a major impact of fishing on the biomass and size structure of nektobenthic carnivorous fish. However, those changes did not modify the diversity of the trophic resources used by the assemblage, the pattern of resource partitioning between species, or the degree of trophic redundancy. These results add to recent evidence suggesting that MPAs implemented in fished seascapes may fail to restore the original structure of the food webs that once existed in pre-fished ecosystems because regional decimation and extinction of highly mobile predators prevent recovering the original diversity of predators at local scales, even in no-take areas. If so, more strict local fishing regulations are unlikely to restore the original diversity of high trophic level carnivores and restoration goals should be reframed in terms of an objective that is less unrealistic than restoring the pre-fished condition while still recovering aspects of the historical trophic structure.

Evaluation of Sustainable Utilization of African Marine Fishery Resources

Sustainable utilization evaluation is the basis for ensuring the sustainable exploitation of fisheries’ resources. This paper explores the changes in the mean trophic level of African marine fish catches during a 70-year period based on the statistical data on marine fisheries’ catches in Africa from 1950–2019, provided by the FAO in, order to determine the sustainable utilization of Africa’s fishery resources. The results indicate that although the marine fishery resources of African coastal countries have great variability, their exploitation has roughly gone through the stages of under-exploitation, rapid exploitation, and over-exploitation. Currently, marine fisheries in North and Central Africa are characterized by sustainable exploitation, while East, West, and Southern Africa are in a state of overfishing. The study implicates that African countries should establish a real-time monitoring system for marine fishery resources as soon as possible in order to dynamically grasp the actual changes in fish community structure due to fishing activities, ensure transparency in management and decision making, enact marine regulations to restrict massive fishing by overseas fleets, issue fisheries licenses cautiously, adopt conservative resource conservation policies, and enforce actions to achieve sustainable fisheries development.

Effects of anomalous climatic events on the structure of fish larvae assemblages in the eastern Amazon

The reproduction of neotropical fish is linked to environmental stimuli that act as triggers in this process. Thus, it is possible to affirm that specific environmental changes can delimit most fish’s period and reproductive success. El Niño Southern Oscillation phenomena (ENSO) influence rainfall and, consequently, hydrological dynamics, affecting several fish population aspects, especially reproductive aspects. However, in the Amazon, empirical evidence of the effect of anomalous climatic events on fish reproduction is incipient. In this sense, we investigated the taxonomic and functional structure of parental fish larvae stocks and how species modulate their reproductive activities before (2013 and 2014) and during La Niña (2018) and El Niño (2019) events. The data evidence that the larval assemblages suffered alterations in the taxonomic and functional composition between the three analyzed periods and a pattern of temporal distribution with a high influence of environmental variables. Flow, pH, and electrical conductivity were the most important variables to modulate fish reproductive intensity between periods. The species seem to respond to combinations of these variables that reflect environmental conditions conducive to biological recruitment according to their ecological characteristics, allowing the perpetuation or decline of their abundance in each period. All species of commercial interest associated with the neutral period showed a sharp decline in the subsequent moments. These results suggest that the incidence of anomalous climatic events added to regional fisheries exploitation can negatively affect the phenology and demographic patterns of larvae assemblages on a short temporal scale. During the neutral period, the community was dominated by larvae of periodic large, herbivores, piscivores, epibenthic maneuverable, and nektonic burst swimmers. The decrease in the abundance of certain functional groups at the neutral and La Niña period favored an accelerated ecological succession during the El Niño period, due to the increase of species from basal trophic levels (planktivores), generalists (omnivores), highly resilient (intermediate strategists), sedentary, short-distance migrants and little commercially exploited. Thus, the results contribute to the understanding of the interactions between anomalous climatic events and the reproduction of fish with different ecological characteristics in the Amazon River.

Genetic population dynamics of the critically endangered scalloped hammerhead shark (Sphyrna lewini) in the Eastern Tropical Pacific.

The scalloped hammerhead shark, Sphyrna lewini, is a Critically Endangered, migratory species known for its tendency to form iconic and visually spectacular large aggregations. Herein, we investigated the population genetic dynamics of the scalloped hammerhead across much of its distribution in the Eastern Tropical Pacific (ETP), ranging from Costa Rica to Ecuador, focusing on young-of-year animals from putative coastal nursery areas and adult females from seasonal aggregations that form in the northern Galápagos Islands. Nuclear microsatellites and partial mitochondrial control region sequences showed little evidence of population structure suggesting that scalloped hammerheads in this ETP region comprise a single genetic stock. Galápagos aggregations of adults were not comprised of related individuals, suggesting that kinship does not play a role in the formation of the repeated, annual gatherings at these remote offshore locations. Despite high levels of fisheries exploitation of this species in the ETP, the adult scalloped hammerheads here showed greater genetic diversity compared with adult conspecifics from other parts of the species' global distribution. A phylogeographic analysis of available, globally sourced, mitochondrial control region sequence data (n= 1818 sequences) revealed that scalloped hammerheads comprise three distinct matrilines corresponding to the three major world ocean basins, highlighting the need for conservation of these evolutionarily unique lineages. This study provides the first view of the genetic properties of a scalloped hammerhead aggregation, and the largest sample size-based investigation of population structure and phylogeography of this species in the ETP to date.

Are Chilimira Fishers of Engraulicypris sardella (Günther, 1868) in Lake Malawi Productive? The Case of Nkhotakota District

An ecological shift has populated Engraulicypris sardella as a livelihood and economic drive among fishers in Malawi. However, the paucity of biological information regarding E. sardella limits the effective monitoring and sustainable management of the fishery. This has created a heavily invested fishery in terms of the effort put into fishing, but it is poorly managed. Moreover, the current production capacity from the fishery has a negligible impact on lessening the shortfall of the national fish demand, indicating its underperformance. Therefore, the productive efficiency of Lake Malawi Chilimira fishers in exploiting E. sardella was analysed. A multi-stage sampling technique was used to sample 355 Chilimira fishers between July and October 2021. Results from the translog stochastic frontier model revealed that Chilimira fishers had an overall mean technical efficiency of 60% that ranged between 21% and 92%. This indicates that Chilimira fishers are 40% technically inefficient in exploiting E. sardella. The fishing inputs of bunt area, light emitting diode (LED) bulbs, and mesh size significantly contributed to technical efficiency, whereas boat size, fishing depth, number of hauls, and mosquito net lining significantly reduced the technical inefficiency. On average, the Chilimira fishery is operating with increasing returns to scale with bunt area, the quantity of fuel (litres), and the number of LED bulbs having positive input–output elasticity. This means that new developments in the fishery, including LED bulbs, increased bunt area, and boat size, are key factors that will improve fishing efficiency for sustainable fishery exploitation. In contrast, illegal fishing units of small bunt mesh size and mosquito net lining at the bunt threaten the sustainability of the fishery. It is, therefore, important that relevant stakeholders put policy measures in place that promote sustainable fishing effort approaches in exploiting the virgin offshore fishery to maximise catch.

Uncovering ecological regime shifts in the Sea of Marmara and reconsidering management strategies

Ecosystem regime shifts can alter ecosystem services, affect human well-being, and trigger policy conflicts due to economic losses and reductions in societal and environmental benefits. Intensive anthropogenic activities make the Sea of Marmara ecosystem suffer from nearly all existing available types of ecosystem pressures such as biological degradation, exposure to hydrological processes, nutrient and organic matter enrichment, plastic pollution, ocean warming, resulting in deterioration of habitats. In this study, using an integrated ecosystem assessment, we investigated for the first time the historical development and ecosystem state of the Sea of Marmara. Multivariate analyses were applied to the most comprehensive and unique long-term data sets of 9 biotic and 15 abiotic variables for ecosystem state and drivers respectively, from 1986 to 2020. Observed changes were confirmed by detecting shifts in the datasets. The Sea of Marmara ecosystem was classified into three regimes: i) an early initial state regime under the top-down control of predatory medium pelagic fish and fisheries exploitation until mid-1990s, ii) a transitional regime between mid-1990s and mid-2010s as from ecosystem restructuring, and iii) an alternate state late regime with prevailing impacts of climate change from mid-2010s until 2020. During the 20 years transitional regime, three different phases were also characterized; i) the 1st phase between mid-1990s and early 2000s with its gradual change in ecosystem state from a decrease in predators and significant shift in physical drivers of the ecosystem, ii) the 2nd phase between 2000 and mid-2000s with a strong shift in ecosystem state, an ongoing increase in climate indices and fishing mortality, and a gradual decrease in water quality; and iii) the 3rd phase between mid-2000s and mid-2010s with the reorganization of the ecosystem dominated by small pelagic fish and ameliorated water quality. During late regime, we observed that most of the biotic variables, mainly fish biomass, and climate variables did not return to their initial state despite the improvement in some abiotic variables such as water quality. We identify these observed changes in the SoM ecosystem as a non-linear regime shift. Finally, we also developed concrete suggestions for improved regional management.

Decadal changes in parrotfish assemblages around reefs of Guam, Micronesia

Modern coral reefs face substantial threats that endanger their capacity to function and provide resources for human populations. Chronic human pressure through exploitation and land-based pollution has led to reef degradation and lower productivity. More recently, this pressure is compounded with successive episodes of coral bleaching across the tropical oceans. However, response trajectories of reef resources to exploitation, habitat degradation, and local management may not be straightforward, as these ecosystems are incredibly complex. We employed a comprehensive and standardized survey of parrotfish assemblages within reef systems in Guam to examine trajectories of biomass and function across a decade of change. Parrotfishes represent one of the most commercially and ecologically important coastal resources throughout Micronesia. We found that parrotfish biomass declined by nearly 30% over the course of ten years, with concomitant decreases in grazing and bioerosion rates at a similar magnitude. There was evidence of fishery exploitation playing a role, but overall patterns were not always aligned with the hypothesis of fishery-induced decline. For example, two-thirds of marine-protected area sites declined in biomass and mean body length was stable for several highly targeted species. Further, most biomass decline stemmed from small species with higher resilience to fishery exploitation, whereby three of the most vulnerable fishery target species either maintained or increased total biomass. The ultimate drivers of parrotfish assemblage trajectories in Guam are likely a complex mixture of exploitation, habitat change from multiple stressors, and responses to management measures. However, the potential future decline in fishery production and ecological function is substantial and merits continuous monitoring and proactive management.

A livelihoods assessment of new entrants within the US fisheries agriculture continuum

Commercial fishing and farming are critical industries that ensure national food security, provide employment opportunities, and contribute to the well-being of rural livelihoods and communities. In the U.S., both industries face a looming challenge in the aging of their workforce and concerns about their long-term resilience. In this study, we document the issues faced by young farmers and fishers in the U.S. using a systematic literature review and expert interviews. These issues are analyzed and contextualized using the capital assets framework or livelihoods approach, which includes financial, physical, natural, human, and social capital, to understand the structural issues faced by individuals seeking occupations in commercial fishing and farming. We then examine the diverse programming that has been developed to facilitate entry into both industries across the capital assets framework. Fundamental issues continue to impede entry into both industries, but the mechanisms that have been developed in farming to address these challenges are far richer in variety, scope, and depth. This is at least in part due to the long-term national recognition of the aging crisis in farming and the centralized nature of data collections, funding, and programs that exist to help beginning farmers. In stark comparison, piecemeal efforts have been undertaken across the country to address fisheries entry issues resulting in disparate, micro-level programs that address a singular capital asset at a very localized scale. The interrelatedness of these issues across these industries and how they are being addressed provides a vantage point that is imperative for building knowledge and understanding of dynamics that may be tackled with cross-cutting programs.

Residence, activity patterns and behaviour of the giant mottled eel Anguilla marmorata in two freshwater protected areas in the Philippines

Abstract Despite the giant mottled eel Anguilla marmorata being a widely distributed and locally exploited species throughout the Indo Pacific region, understanding of its life history, behaviour and movement ecology remains limited. Knowledge of animal spatial ecology is essential for the effective design and siting of aquatic protected areas. In the current study, acoustic telemetry was used to quantify residence and explore the activity patterns and behaviour of A. marmorata (n = 68) in two freshwater protected areas (FPAs) for the first time in the Cagayan River Basin, Philippines. The results demonstrated that FPAs of only 1 km length provided refuge for A. marmorata for an average of 25–26% of the tracked period. Residence and activity patterns varied with habitat type. In pool and riffle habitat, activity reduced with increased river flow, and eel, particularly larger individuals, were more strongly nocturnal than those in the deep pooled, slow flowing habitat. Typhoon events displaced many individuals, particularly in the pool and riffle habitat, with only 3% returning to the FPA within the study. Findings are discussed within the context of selecting FPA sites to optimize eel protection within catchments experiencing high non‐selective fisheries exploitation and other threats.

Evaluating Catch-Only Methods to Inform Fisheries Management in the East China Sea

China contributes the largest catches to global marine wild-capture fisheries. The majority of them are harvested from China Seas which are highly productive, but are facing heavy fisheries exploitation. The status of exploited fisheries stocks in China Seas have remained largely unknown due to severe data-limited conditions, which hindered their sustainable use and effective management. Although the off-the-shelf use of catch-only methods (COMs) has been cautioned because of their poor estimation performance, such methods have been increasingly applied to infer the status of exploited stocks in China Seas without performance evaluation. In this study, we established an empirical approach to evaluate the performance of a suite of COMs in predicting stock biomass status for the data-limited fisheries in the East China Sea (ECS) from data-rich stocks with similar characteristics in the RAM Legacy Stock Assessment Database (RLSADB). The results confirmed that ensemble approaches performed better than the individual COMs in estimating the mean of stock biomass status for data-rich stocks selected from RLSADB. By contrast, mechanistic COMs demonstrated more accurate estimates when predicting the trend of stock biomass status. The stock status of commercial fisheries in ECS estimated by three mechanistic COMs (Catch-MSY, CMSY, and OCOM) was likely too optimistic for most species. We suggest that China establish its national database and develop and implement regular monitoring programs to satisfy formal statistical stock assessment for its coastal fisheries.

INFLUENCE OF BENTHIC FAUNA ON HYDROCHEMISTRY ANDSEDIMENT IN SASTHAMKOTTA LAKE IN SOUTHERN KERALA, INDIA

Sasthamkotta Lake is the largest freshwater water body of Kerala with great ecological significance, playing also pivotal role in the supply of water for drinking, agriculture, fishery exploitation, industrial activities, frivolous navigation and water tourism. Due to their importance, the environmental conditions in the Sasthamkotta lake have engrossed an better public attention in present society. The concentrations of various physico-chemical parameters of water and sediment are not exceeding environmental standards. Benthic samples revealed 8 species belonging to Order Diptera, Order Trichoptera and Order Tubificida. The results obtained from the study showed good ecological condition despite numerous local and regional natural and anthropogenic interventions.

Patron-client relationships shape value chains in an Indonesian island-based fisheries system

Fishing is vital to millions of people in Southeast Asia. Overfishing along with climate-induced stressors have presented significant challenges to managers. Solutions for fisheries management in the region, however, tend to narrowly focus on production and catch restrictions despite the importance of local economies and relationships. For example, the role of networks known as patron-client systems are understood by scholars and local populations as important drivers of fisheries exploitation in Indonesia, but policy is rarely directed at them. Here, we perform value chain analysis to better understand the socioeconomic factors that mediate fish catch, distribution, and governance outcomes in an Indonesian fishing community. The community’s social context spurred the following research questions: i) In what ways does the regional fish trading system influence fisheries value chains; and ii) How does the current structure of trade align with fisheries and fishing actors on the island? Survey-based fieldwork collected data on species composition, revenue, and buyer/seller relationships from the point of catch to sale. These results showed that patrons earn disproportionate trading benefits compared to fishing clients, including higher revenues, bargaining power, and flexibility from their central position as lenders. Findings also revealed a strong connection between pelagic-based fishing crews and the wider market system, which mediates the trade of fish off-island. Given the links between trading hierarchies and fish flows in our study, we argue that efforts to enhance fisheries governance would be most effective if introduced through off-island auctioneers since they have significant power in controlling fish catch and distribution.

Biodiversity underpins fisheries resilience to exploitation in the Amazon river basin.

Inland fisheries feed greater than 150 million people globally, yet their status is rarely assessed due to their socio-ecological complexity and pervasive lack of data. Here, we leverage an unprecedented landings time series from the Amazon, Earth's largest river basin, together with theoretical food web models to examine (i) taxonomic and trait-based signatures of exploitation in inland fish landings and (ii) implications of changing biodiversity for fisheries resilience. In both landings time series and theory, we find that multi-species exploitation of diverse inland fisheries results in a hump-shaped landings evenness curve. Along this trajectory, abundant and large species are sequentially replaced with faster growing and smaller species. Further theoretical analysis indicates that harvests can be maintained for a period of time but that continued biodiversity depletion reduces the pool of compensating species and consequently diminishes fisheries resilience. Critically, higher fisheries biodiversity can delay fishery collapse. Although existing landings data provide an incomplete snapshot of long-term dynamics, our results suggest that multi-species exploitation is affecting freshwater biodiversity and eroding fisheries resilience in the Amazon. More broadly, we conclude that trends in landings evenness could characterize multi-species fisheries development and aid in assessing their sustainability.

A Twilight Zone Episode: Historical Expansion of the Soviet Union’s Fishing Fleet and the Exploitation of Mesopelagic Fisheries in the Southern Ocean

A Twilight Zone Episode: Historical Expansion of the Soviet Union’s Fishing Fleet and the Exploitation of Mesopelagic Fisheries in the Southern Ocean

Age structure affects population productivity in an exploited fish species

Long-term changes in the age and size structure of animal populations are well documented, yet their impacts on population productivity are poorly understood. Fishery exploitation can be a major driver of changes in population age-size structure because fisheries significantly increase mortality and often selectively remove larger and older fish. Climate change is another potential driver of shifts in the demographic structure of fish populations. Northeast Arctic (NEA) cod is the largest population of Atlantic cod (Gadus morhua) and one of the world's most important commercial fish stocks. This population has experienced considerable changes in population age-size structure over the past century, largely in response to fishing. In this study, we investigate whether changes in spawner age structure have affected population productivity in NEA cod, measured as recruits per spawning stock biomass, over the past 75 years. We find evidence that shifts in age structure toward younger spawners negatively affect population productivity, implying higher recruitment success when the spawning stock is composed of older individuals. The positive effect of an older spawning stock is likely linked to maternal effects and higher reproductive output of larger females. Our results indicate a threefold difference in productivity between the youngest and oldest spawning stock that has been observed since the 1950s. Further, our results suggest a positive effect of environmental temperature and a negative effect of intraspecific cannibalism by older juveniles on population productivity, which partly masked the effect of spawner age structure unless accounted for in the model. Collectively, these findings emphasize the importance of population age structure for the productivity of fish populations and suggest that harvest-induced demographic changes can have negative feedbacks for fisheries that lead to a younger spawning stock. Incorporating demographic data into harvest strategies could thus facilitate sustainable fishery management.

Performance Comparison of Three Data-Poor Methods With Various Types of Data on Assessing Southern Atlantic Albacore Fishery

In the world, more than 80% of the fisheries by numbers and about half of the catches have not been formally analyzed and evaluated due to limited data. It has led to the fast growth of data-poor evaluation methods. There have been various studies carried out on the comparative performance of data-poor and data-moderate methods in evaluating fishery exploitation status. However, most studies to date have focused on coastal fish stocks with simple data sources. It is important to pay attention to high sea fisheries because they are exploited by multiple countries, fishing gears and data may be divrsified and inconsistent. Furthermore, a comparison of the performance of catch-based, length-based, and abundance-based methods to estimate fishery status is needed. This study is the first attempt to apply catch-based, length-based, and abundance-based data-poor methods to stock assessment for an oceanic tuna fishery and to compare the performance with a data-moderate model. Results showed that the three data-poor methods with various types of data did not produce an entirely consistent stock status of the southern Atlantic albacore (Thunnus alalunga) fishery in 2005, as the estimated B2005/BMSY ranged from 0.688 to 1.3 and F2005/FMSY ranged from 0.708 to 1.6. The Monte Carlo Catch maximum sustainable yield model (CMSY) produced a similar time series of B/BMSY and F/FMSY and stock status (recovering) to the Bayesian state-space Schaefer model (BSM). The abundance-based method (AMSY) gave the most conservative condition (overfished) of this fishery. Sensitivity analysis showed the results of the length-based Bayesian biomass estimation method (LBB) are sensitive to Linf settings, and the results with higher Linf were similar to those of other models. However, the LBB results with setting Linf at lower levels produced more optimistic conditions (healthy). Our results highlight that attention should be paid to the settings of model parameter priors and different trends implied in various types of data when using these data-poor methods.

An assessment of sampling approaches for estimating growth from fishery-dependent biological samples

Abstract Accuracy of fish growth estimates depends greatly on how samples are collected. A total of three common sampling strategies are random, fixed otolith sampling (FOS), and proportional otolith sampling (POS). Random sampling is inefficient and rarely random. While POS has been shown to produce more accurate estimates of growth compared to FOS under ideal conditions, it is unclear how variables such as sample size, fishery selectivity, and fishing mortality influence sampling bias. Simulated age-at-length observations from two tropical deepwater species were used to evaluate the accuracy of von Bertalanffy growth parameter estimates comparing FOS and POS for a fast-growing, short-lived fish (Prisitipomoides auricilla) and a slow-growing, long-lived fish (Etelis coruscans). A total of 24 scenarios were tested to examine the influence of sample size, minimum size selected in the fishery, fishery exploitation rates, and supplemental sampling on growth parameter estimates. Furthermore, tests were applied to real fishery age–length observations for P. auricilla. POS consistently performed better than FOS, especially when the catch was representative of the population. However, FOS performed better when catch was not representative. This research demonstrates the importance of considering effects of fishery selectivity, fishing mortality, and sample size on sampling strategy and provides a tool to select an appropriate approach.

Projected climate change impacts on the ecosystems of the Agulhas Bank, South Africa

Marine ecosystems are expected to be increasingly affected by climate change, impacting their physical and biogeochemical environment. Changes in primary production, temperatures and hence species distribution, may lead to critical consequences for fishery exploitation. Therefore, future projections are essential to develop sustainable strategies and climate change adaptation plans for fisheries, and fishery-dependent societies. In this study, we focus on the Agulhas Bank, a broad extension of the continental shelf of the South African coast, along which flows the western boundary Agulhas Current. The Agulhas Bank is known for being biologically productive and is an important nursery ground for many commercially exploited fish species, including the chokka squid fishery, a vital source of income for many people in the Eastern Cape Province. Squid catches manifest strong interannual fluctuations, at times causing fishery crashes. Additional impacts due to climate change will have significant socio-economic consequences for this all-important fishery. To investigate future variations of the physical and biogeochemical environment on the Agulhas Bank, we used the global ocean model NEMO-MEDUSA, forced by the high emissions scenario RCP8.5. Our simulations show a significant increase in sea surface temperature and bottom temperature, but limited changes in primary production. Projections highlight an increase in current velocity on the Agulhas Bank throughout the course of this century, induced by an onshore shift of the Agulhas current. This current shift may pose a threat to squid recruitment success as a large fraction of squid paralarvae may be removed from their shelf feeding grounds and lost to the greater ocean via the Agulhas current. The results further show that planktonic food for the paralarvae is less likely to become the main limiting factor in the future, while increasing temperatures may affect growth rates and spawning success.