Optimising recreational harvests of blue cod: The effects of catch-and-release mortality and size selectivity

A yield-per-recruit model is developed for the recreational fishery on blue cod (Parapercis colias: Pinguipedidae) in the Marlborough Sounds, New Zealand. The model incorporates sex differences in growth rates, protogyny, minimum size limits, catch-and-release mortality and size-selective fishing. Mortality of released fish due to hooking damage and post-release predation is a potentially significant factor for blue cod management. High levels of catch-and-release mortality favour small minimum size limits and reduced fishing intensity. Even in the absence of size limits, hook and line fishing for blue cod is highly selective on larger fish and this greatly reduces the potential impact of catch-and-release mortality on yields and management choices. Catch-and-release mortality will also lower the spawning stock biomass-per-recruit and therefore has the potential to impact on stock sustainability as well as yields. In protogynous species the effects of fishing on spawning stock biomass will be different for males and females and it is important to model these separately, as well as understanding the cues for, or timing and extent of, sex change. Catch-and-release mortality can also slow the recovery of stocks when no-take rules still allow fishing for other species and therefore by-catch of the species targeted for protection. It is suggested that a small reduction in size limit and a small increase in daily bag limit relative to present regulations, would result in optimal yields from this fishery. Predation on fish released by recreational anglers is less widely reported than mortality due to hooking damage but both have the potential to negate the benefits of minimum size limits.     

Effects of cryptic mortality and the hidden costs of using length limits in fishery management

Fishery collapses cause substantial economic and ecological harm, but common management actions often fail to prevent overfishing. Minimum length limits are perhaps the most common fishing regulation used in both commercial and recreational fisheries, but their conservation benefits can be influenced by discard mortality of fish caught and released below the legal length. We constructed a computer model to evaluate how discard mortality could influence the conservation utility of minimum length regulations. We evaluated policy performance across two disparate fish life‐history types: short‐lived high‐productivity (SLHP) and long‐lived low‐productivity (LLLP) species. For the life‐history types, fishing mortality rates and minimum length limits that we examined, length limits alone generally failed to achieve sustainability when discard mortality rate exceeded about 0.2 for SLHP species and 0.05 for LLLP species. At these levels of discard mortality, reductions in overall fishing mortality (e.g. lower fishing effort) were required to prevent recruitment overfishing if fishing mortality was high. Similarly, relatively low discard mortality rates (>0.05) rendered maximum yield unobtainable and caused a substantial shift in the shape of the yield response surfaces. An analysis of fishery efficiency showed that length limits caused the simulated fisheries to be much less efficient, potentially exposing the target species and ecosystem to increased negative effects of the fishing process. Our findings suggest that for overexploited fisheries with moderate‐to‐high discard mortality rates, reductions in fishing mortality will be required to meet management goals. Resource managers should carefully consider impacts of cryptic mortality sources (e.g. discard mortality) on fishery sustainability, especially in recreational fisheries where release rates are high and effort is increasing in many areas of the world.     

死亡因素对放流明对虾群体资源变动及生物学参考点影响的量化评估

为评估环境突变、被捕食、纳潮、非法捕捞和交尾死亡对资源量和渔获量的影响,及5种死亡因素和与生长有关的参数引入不确定性对估算生物学参考点(Fmax和F0.1)的影响,基于发展的可应用于研究放流增殖渔业的YPR(yield per recruitment)模型,模拟5种死亡因素不同水平下放流中国明对虾的资源变动规律。结果显示,环境突变、被捕食、纳潮、非法捕捞和交尾死亡水平越高,单位放流资源量和渔获量越少,交尾死亡尤其对累计单位放流渔获量的影响明显;在未引入不确定性时,作用于开捕前的环境突变、被捕食、纳潮和非法捕捞死亡的不同水平对生物学参考点无影响,与生长有关的参数及5种死亡因素引入不确定性可能存在低估F0.1和Fmax的现象。研究表明,减小与放流技术有关的环境突变、被捕食、纳潮和非法捕捞死亡水平对提高放流中国明对虾渔业效果有明显的作用,交尾死亡发生的时间及死亡水平对放流中国明对虾渔获有直接的影响,当参数引入不确定性时进行放流中国明对虾资源评估,生物学参考点的中位数较均值抗不确定性干扰能力更强。     

Economic impact of juvenile fishing in a tropical multi-gear multi-species fishery

In open access marine fisheries, the non-targeted catches in the form of juveniles are detrimental, as this would reduce future yield and subsequent recruitment to the fishery. The proliferating impact of juvenile fishing is much more intense in a multi-gear multi-species fishery like Indian marine fisheries, where intra- and inter-sectoral conflicts exist. Marine fishing in India is contributing significantly to the country's economic growth and the coastal livelihood security. Although the recent changes in the techno-harvesting pattern of inshore fisheries of the country has led to a remarkable increase in fish landings, the problem of by-catch and targeted juvenile fishing is ever increasing. The present analysis shows that the contribution in the form of annual average profit by various craft–gear combinations is often not sufficient to compensate the overall loss generated by the same to the fishery through the harvest of juvenile fishes. Even though the fishermen gain some transient economic incentives from the juveniles landed, the estimated economic loss calculated was at about US$ 19,445 million year⁻¹ from the mechanised as well as motorised sector. Both intergenerational and conventional discounting was applied to show the net present value (NPV) of future loss due to juvenile fishing. Some of the less capital intensive gears also substantially contribute towards the economic deficit caused by juvenile fishing. We suggest that, while considering the ecosystem impacts of accidental by-catch and intentional juvenile fishing, the economic impacts also should be taken into account prior to formulating any management measures. The study provides an insight to the cost of juvenile fishing in a multi-species multi-gear fishery, where a homogeneous management system is ineffective. The possible causes of increased growth overfishing in the country and subsequent economic loss to the industry are also discussed.     

浙江南部海域银姑鱼的生活史参数估算及资源评价

为了评估银姑鱼资源开发状态，实验根据2016年在浙江南部海域底拖网的调查数据，研究了银姑鱼的生活史参数，并基于单位补充量模型对其资源状态进行评价，进而探讨不同自然死亡系数和捕捞选择性对资源评价结果的影响。结果显示，银姑鱼渐近体长估计值为25.36 cm，生长速率为0.32/年，当前开捕体长(13.52 cm)远小于其初次性成熟体长(17.79 cm)；自然死亡系数估计值为0.74，总死亡系数为2.62，当前捕捞死亡系数为1.88。基于以上参数，构建了单位补充量渔获量YPR模型和单位补充量亲体生物量SSBR模型，随着F的增加，YPR先增大后减小，而SSBR则减少。银姑鱼生物学参考点F_0.1为0.78，F_max为3.43，F_20%为0.66，F_40%为0.33，可知当前捕捞强度远大于防止补充型过度捕捞警戒线F_20%。敏感性分析结果显示，自然死亡系数的不确定性将明显影响单位补充量模型的研究结果和相关生物学参考点的估算值，而不同选择性系数，尤其是开捕体长，也直接影响单位补充量模型的结果。研究表明，当前浙江南部近海银姑鱼种群已处于补充型过度捕捞状态，为维持渔业资源的可持续发展，建议适当减小开发力度，增大开捕体长；为提高资源状态评价的准确性，建议减小自然死亡系数的不确定性。本研究可为银姑鱼资源的养护和管理提供科学建议。     

Effects of exploitation on age, growth and mortality of the blackspot snapper, Lutjanus fulviflamma, at Mafia Island, Tanzania

Abstract Estimates of the growth parameters (L_∞ and K), mortality coefficients (Z, M and F) and exploitation rate (E) for the blackspot snapper, Lutjanus fulviflamma (Forsskål) from the Mafia Island Marine Park (MIMP) and adjacent intensively fished areas in Tanzania were determined. Sectioned otoliths showed that L. fulviflamma in the MIMP attained a maximum age of 18 years, with a high proportion of fish between 6 and 10 years old. The maximum age was 8 years in the intensively fished areas, with a preponderance of 2‐ and 4‐year‐old fish. The size structures of the populations in the MIMP and that in the intensively fished areas were markedly different, with the MIMP fish averaging (±SE) 211.4 ± 0.38 mm TL, but 154.6 ± 0.32 mm TL in the intensively fished areas. The von Bertalanffy growth parameters were L_∞ = 290.3 mm TL, K = 0.15 year^?1 and t₀ = ?2.7 years. There was no significant difference in growth between the four populations (L_∞: F‐stat = 0.14, P = 1.000, and K: F‐stat = 0.26, P = 0.992). Total mortality was 0.55 and 1.64 year^?1 in the MIMP and intensively fished areas, respectively, natural mortality 0.27 year^?1 and fishing mortality 0.18 and 1.37 year^?1 in the MIMP and intensively fished areas, respectively. The exploitation rate was 0.51 and 0.84 in the MIMP and intensively fished areas, respectively. The artisanal seine net fishery is directed mainly at younger fish in the intensively fished areas resulting in growth overfishing. The protracted life span, the slow growth and natural mortality rates imply that L. fulviflamma is vulnerable to overfishing and that the protection provided by the park, although limited, is vital for sustaining the fishery at Mafia Island.     

Stock assessment of the blue jack mackerel,Trachurus picturatus,in the North‐eastern Atlantic

A total of 49,151 blue jack mackerel, Trachurus picturatus, (Bowdich) was collected in Madeira Island (North‐eastern Atlantic) between 2002 and 2016 to evaluate possible influence of fishing on landings and reproductive parameters. A decreasing trend in the length composition was observed over the study period and length at first maturity decreased by 2.78 cm TL. Maximum yield per recruit decreased from 2002 to 2016 but the corresponding fishing mortality was constant (F_max = 0.4/year). Considering the fishing mortality level in 2016, it is evident that the stock may be exploited beyond its sustainability limit. Amendments of the purse‐seine fishing regulations and implementation of measures to reduce fishing effort are suggested.     

澳洲鲭太平洋群系的资源评估与管理策略

澳洲鲭是西北太平洋重要的经济种类,了解和掌握澳洲鲭太平洋群系资源开发状况对确保其可持续利用具有重要的意义。根据日本中央水产研究所提供的1995—2015年澳洲鲭太平洋群系的生产统计和资源调查资料,利用基于年龄结构的实际种群模型和单位补充量产量模型等进行资源量评估,分析澳洲鲭太平洋群系资源利用情况及其管理策略。结果显示,历年澳洲鲭太平洋群系资源量虽有波动但仍保持在较高水平,2015年资源量最高约为65万t;年平均捕捞死亡系数呈波动下降趋势,2015年捕捞死亡系数只有0.15,近五年平均捕捞死亡系数Fcur=0.33,单位补充量亲体量是未开发时的32.7%,不存在生长型捕捞过度,也不存在补充型捕捞过度,处于可持续开发状态。研究还探讨了水温变化引起自然死亡波动以及不同开捕年龄对澳洲鲭太平洋群系资源状况的影响。研究表明,该渔业目前开发和利用程度合理,建议使用F0.1做为管理参考点进行渔业资源的管理。     

Forecasting fish stock dynamics under climate change: Baltic herring (Clupea harengus) as a case study

Climate change and anthropogenic disturbances may affect marine populations and ecosystems through multiple pathways. In this study we present a framework in which we integrate existing models and knowledge on basic regulatory processes to investigate the potential impact of future scenarios of fisheries exploitation and climate change on the temporal dynamics of the central Baltic herring stock. Alternative scenarios of increasing sea surface temperature and decreasing salinity of the Baltic Sea from a global climate model were combined with two alternative fishing scenarios, and their direct and ecosystem‐mediated effects (i.e., through predation by cod and competition with sprat) on the herring population were evaluated for the period 2010–2050. Gradual increase in temperature has a positive impact on the long‐term productivity of the herring stock, but it has the potential to enhance the recovery of the herring stock only in combination with sustainable fisheries management (i.e., F_msy). Conversely, projections of herring spawning stock biomass (SSB) were generally low under elevated fishing mortality levels (F_high), comparable with those experienced by the stock during the 1990s. Under the combined effects of long‐term warming and high fishing mortality uncertainty in herring SSB projections was higher and increasing for the duration of the forecasts, suggesting a synergistic effect of fishery exploitation and climate forcing on fish populations dynamics. Our study shows that simulations of long‐term fish dynamics can be an informative tool to derive expectations of the potential long‐term impact of alternative future scenarios of exploitation and climate change.     

Ecologically and evolutionarily sustainable fishing of the pikeperch Sander lucioperca: Lake Oulujärvi as an example

Due to the multitude of participants and a diverse range of fishing gear used freshwater fisheries are often managed using minimum size limits (MSL) rather than regulations of total fishing effort. However, a concern has arisen whether attempts to improve ecological sustainability of fisheries by increasing MSLs would induce undesired adaptations to selective fishing. We examined the ecological and evolutionary impacts of varying fishing mortality rates under varying MSLs, with and without stockings, in an age-, size-, and maturity-structured evolutionary model which was parameterized for the Lake Oulujärvi pikeperch, Sander lucioperca. We found that at the current level of harvesting (fishing mortality rate, F = 0.7) and stockings (430 000 year⁻¹), and under the assumption of strongly density-dependent growth, the nation-wide MSL of 370 mm maximizes theoretical biomass yield in a deterministic model but does not prevent severe recruitment overfishing under further increased fishing pressures or stochasticity in recruitment success. The recently imposed, local MSL of 450 mm better ensures stable yields, and even increases them if individual growth is density-independent, but further increase of MSL to 500 mm would already reduce yield especially if there was discard mortality for undersized fish. Given density-dependent growth, equal survival between wild and stocked fish, and sustainable fishing mortality rate, stockings do not increase yield or significantly improve the stability of yields. Evolutionarily stable size at maturation decreases under strong fishing mortality, but increased MSLs reduce the magnitude of this undesired effect. Negatively size-dependent natural mortality was found to have a positive effect on the otherwise negative selection for length-at-age. Increased MSLs also reduce the total selection for decreased length-at-age. Our results support the intentions to increase MSLs in order to improve both ecological and evolutionary sustainability of recreational fisheries.     

Changes in a coral reef fishery along a gradient of fishing pressure in an Indonesian marine protected area

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Gulf menhaden (Brevoortia patronus) in the U.S. Gulf of Mexico: Fishery characteristics and biological reference points for management

Gulf menhaden, Brevoortia patronus, plays a key ecological role in the northern Gulf of Mexico and supports the second largest commercial fishery by weight in the United States. Here we describe that fishery and propose biological reference points (BRPs) for its management. The BRPs represent targets and limits of both fishing mortality rate (F) and population fecundity (Ψ), where target is defined as the management goal, and limit, a value to be avoided (F < F_Limit and Ψ > Ψ_Limit). We assess stock status relative to the BRPs by fitting a statistical catch-age model to fishery-dependent and fishery-independent data spanning 1964–2004. Results indicate that in the terminal year neither limit reference point is exceeded (F₂₀₀₄/F_Limit = 0.75 and Ψ₂₀₀₄/Ψ_Limit = 1.86). Of possible concern, however, is a recent increase in fishing mortality and decrease in population fecundity. With these trends, terminal values exceed their targets (F₂₀₀₄/F_Target = 1.16 and Ψ₂₀₀₄/Ψ_Target = 0.93), although by little relative to uncertainty in the estimates. Sensitivity analyses show these results are robust to model assumptions.     

Indicators of unsustainable fishery in the Middle Danube

Fishery in the Danube River basin has been characterised over the past century by increasing fishing levels, illegal fishing practices and poor regulations. However, there is a remarkable lack of available information on the actual status of fish stocks, as well as on the trends and sustainability of fisheries, which poses a problem for the development of adequate policy and management measures. In this study, we assessed the trends in the commercial fishery in the Middle Danube in Serbia during 1969–1989 and 2006–2010 by evaluating the temporal changes in life history‐related indicators that might point out unsustainable fishing pressures. Moreover, we present the approach of using the catch‐weighted mean egg‐per‐recruit (EPR) index as a proxy for the overall resilience of fish stocks to fishing. Results indicated a marked shift towards smaller fish that mature earlier and have a shorter lifespan. Landings also shifted towards species at lower trophic levels, with a mean trophic level decline at a rate of approximately 0.16 per decade. Results indicated likely presence of the ‘fishing through the food web’ phenomenon. At the same time, catch‐weighted community mean of the 20% EPR threshold ratio (EPR_20%) increased by 4.2%, indicating the increase of the overall resilience to fishing of the exploited species. Obtained results indicated the importance of using such metrics for the assessments of trends in fishery. The approach and results presented here could be of interest for the scientific community and stakeholders involved in fishery management.     

Estimating rates of mortality in stocks of Metapenaeus macleayi in estuaries of eastern Australia

Estimating rates of mortality is important for assessing stocks and for effectively managing seafood resources. This study reports the first estimates of rates of instantaneous fishing mortality (F) and natural mortality (M) for the commercially important school prawn, Metapenaeus macleayi. Replicated tag-recapture experiments were conducted on two stocks (Clarence River and Wallis Lake) to estimate the catchability coefficient (q) and F, whilst M was estimated from meta-analyses. Experiments were conducted across spatial and temporal scales to consider variability between stocks and variability between fisheries targeting this resource. The catchability coefficient was fitted to tag-recapture data in a population model across a range of M values (0.001-0.025 per day) and average daily F values were calculated. Values of q ranged between 2.03E−04 and 5.43E−02 and, 1.29E−04 and 3.41E−03 for the Clarence River and Wallis Lake stocks, respectively. Average daily F ranged between 2.86E−03 and 1.69 for the Clarence stock and 1.71E−03 and 3.44E−02 for the Wallis stock. With one exception (the November 2004 experiment) there were no differences in q and F values between experiments conducted on the Wallis Lake stock. For the Clarence stock values of q and F varied between years and within years. Factors thought to contribute to this variability were changes in prawn behaviour, differences in sizes of prawns tagged between experiments and differences in the survival of tagged prawns. The catchability coefficient for the Clarence River stock was weakly correlated to greater rates of river discharge. Estimates of F for the Wallis stock, the Clarence stock in 2004-05 and estimates of M were comparable to those reported for other penaeid fisheries world wide. There was no consistent pattern in comparisons of q and F values between the predominantly trawling operation of the Clarence River fishery and the seine netting of the fishery in Wallis Lake.     

Are stock assessment methods too complicated?

This critical review argues that several methods for the estimation and prediction of numbers‐at‐age, fishing mortality coefficients F, and recruitment for a stock of fish are too hard to explain to customers (the fishing industry, managers, etc.) and do not pay enough attention to weaknesses in the supporting data, assumptions and theory. The review is linked to North Sea demersal stocks. First, weaknesses in the various types of data used in North Sea assessments are summarized, i.e. total landings, discards, commercial and research vessel abundance indices, age‐length keys and natural mortality (M). A list of features that an ideal assessment should have is put forward as a basis for comparing different methods. The importance of independence and weighting when combining different types of data in an assessment is stressed. Assessment methods considered are Virtual Population Analysis, ad hoc tuning, extended survivors analysis (XSA), year‐class curves, catch‐at‐age modelling, and state‐space models fitted by Kalman filter or Bayesian methods. Year‐class curves (not to be confused with ‘catch‐curves’) are the favoured method because of their applicability to data sets separately, their visual appeal, simple statistical basis, minimal assumptions, the availability of confidence limits, and the ease with which estimates can be combined from different data sets after separate analyses. They do not estimate absolute stock numbers or F but neither do other methods unless M is accurately known, as is seldom true.     

Population dynamics and fishery benefits of a large legal size of a pelagic sportfish,the Talang queenfish,Scomberoides commersonnianus,in northern Australia

The life history of an increasingly important pelagic commercial and sport fish, the Talang queenfish, Scomberoides commersonnianus, was studied in northern Australia to investigate the stock status and assess current management of the species using minimum legal lengths (MLL). Estimated von Bertalanffy growth parameters were L_∞ = 1404 mm FL, K = 0.10 year⁻¹ and t₀ = −1.21 year⁻¹. There was no significant difference in growth between sexes. Ages ranged from 1 to 11 years with age composition differing between the commercial (mainly 6–7 years) and sport fishery (mainly 2–4 years). Females matured (L₅₀) at 635 mm FL and 4–5 years. Spawning occurred between August and March when mature females were estimated to produce 259,488–2,859,935 eggs per spawning. Natural mortality (M) was estimated as 0.16–0.26 year⁻¹, while the combined fishing mortality (F_current) from commercial and sport fisheries was 0.38–0.48 year⁻¹. Yield-per-recruit analyses revealed that under current MLL limits (no MLL or 45 cm TL) and natural mortality (M = 0.16, 0.2 and 0.26 year⁻¹), F_current exceeded the reference points F_max (0.15–0.22 year⁻¹) and F_0.1 (0.10–0.15 year⁻¹), suggesting the stock may be growth overfished if the current situation remains unchanged. Although a stock–recruitment relationship is unknown, spawning stock biomass-per-recruit analysis indicates the stock may also be recruitment overfished since F_current exceeded the reference points F_25% (0.19–0.24 year⁻¹) and F_40% (0.11–0.15 year⁻¹). Increasing the MLL corresponding to L₅₀ of females (70 cm TL) will greatly improve the yield and long-term sustainability of the stock, and also enhance the sport fishery by increasing the number of larger trophy fish.     

Vital population statistics of the exploited eel stock on the Swedish west coast

The population dynamics and exploitation of the yellow eel (Anguilla anguilla (L.)) stock on the Swedish west coast were studied. In contrast to a generally observed reduction in the recruitment of glass eels in Europe, including in Swedish waters, there was no indication of a decline in the total eel fishery yields along the Swedish west coast. Long-term records of daily catches as well as by test fishing results also shown that this stability in eel fishery yields has not been maintained by an increase in fishery effort, as the catch-per-unit-efforts in the past 20 years have been more or less unchanged. These findings implied that the number of recruits to the fishery has been rather stable, possibly indicating that density-dependent factors at the elver and yellow eel stages may moderate variations in glass eel recruitment. Total instantaneous rate of mortality was estimated from records on eel length distribution in the professional fyke-net fishery. The estimated total mortality rate in an isolated archipelago population on the west coast was chosen as an approximation of the instantaneous rate of natural mortality and net emigration in the west coast eel stock. The differences between these two estimates could, thus be regarded as the mortality that occurred due to fishing. It was found that the eel fishery was very intense and most fish were caught in small sizes, resulting in a low escapement rate of maturing fish.     

Japanese chum salmon stock enhancement: current perspective and future challenges

This study reviews the present status of the Japanese chum salmon Oncorhynchus keta stock enhancement program and considers the ecological sustainability of wild populations while providing fishery production, exemplified by the hatchery-based Kitami region set net fishery. The return rate and the number of returns have been historically high in the Sea of Okhotsk, but have decreased in other regions since 2005. Natural spawning of chum salmon occurred in at least 160 rivers in Hokkaido. The genetic diversity of Japanese chum salmon was similar to or higher than that of other Pacific Rim populations. Numbers of alleles were high at microsatellite loci, but the loss of rare haplotypes was observed in all populations. The estimated N _e /N ratio for the Kitami region was >0.15 % including hatchery and wild fish under the present high fishing pressure. Four regional populations were inferred in Hokkaido, however, genetic differentiation was weak and some river-populations were nested. Substantial changes in run timing were observed, but it has recovered gradually owing to the recent practice of escapement. Our analyses highlight the importance of juvenile quality and the vital roles of escapements in enhanced and non-enhanced rivers. New research is needed to minimize the genetic risks associated with hatchery programs.     

渔获物平均营养级在渔业可持续性评价中的应用研究进展

高强度的捕捞努力量和渔业管理不力等因素导致全球范围内传统渔业资源的衰退,近年来渔获物平均营养级(MTL,mean trophic level)作为以生态系统为基础的渔业管理评价指标被普遍应用。本文在广泛收集国内外相关文献资料基础上,系统地介绍了MTL在渔业资源评价中的研究进展。已有研究显示,MTL能够利用已知渔获数据来分析,且参数化较为简便,在评价渔业可持续性中优势明显。受以渔获量作为生态系统指标、营养级(TL,trophic level)随体长的变化、渔获统计数据质量、低TL种类的过多捕捞和海域环境富营养化等因素的影响,在评估渔业资源利用状况时,需将MTL与剔除TL小于3.25物种下的3.25MTL、渔业均衡指数(FIB)等营养指标综合分析。此外,综合运用多指标,将营养指标与渔获组成、中上层鱼类与底层鱼类产量的比值、市场价格等指标结合分析,有助于掌握引起MTL变动的因素,更加全面地掌握捕捞活动下鱼类群落结构的实际变化状况。     

Capture for culture: artificial shelters for grouper collection in SE Asia

This paper addresses a little‐discussed relationship between wild capture and mariculture, when the latter involves grow‐out of small wild‐caught fish or invertebrates in captivity. Seafood generated in this way is typically considered to be a form of aquaculture because it is assumed that, for animals removed from the wild when natural mortality is still very high, the protection conferred by culture operations will improve survivorship and enhance production. This assumption does not necessarily, however, apply when animals are removed well past the time of early high mortality. As one example of the implications of an early life‐history phase (ELP) fishery supplying culture operations, a preliminary study was conducted on an ELP fishery supplying live reef fish, especially groupers, in Southeast Asia. Grouper culture depends on both hatchery‐produced and wild‐caught fish which are then grown out to market size. Following interest to develop grow‐out operations in Indonesia, a pilot study was conducted to determine the sizes and capture rates of species of interest to the live fish trade, and to determine the likely environmental footprint of an artificial shelter (gango) type of capture method. From the results of the 15‐month study, we drew inferences regarding the sustainability of this fishing method and requirements of space, fish and materials for a viable grow‐out operation. The results showed that gangos were unselective for either species or size. Only 1.4% of the total fish catch (by number) were target species, mainly the grouper Epinephelus coioides, and most were large (mean total length was 13.6 cm) enough to have bypassed the early high mortality phase. Moreover, there were large non‐target catches that included many food fish species too small to be useful in catches. Given the large number and area of gangos needed for a viable operation, and that many groupers captured could probably have survived to reproduce, the ecological footprint of this approach could be substantial. These results, and literature on other ELP fisheries, suggest that these may often need management, have important links to other capture fishery sectors, and require careful evaluation of potential costs and benefits before introduction or development.