The relationship between the skipjack tuna (Katsuwonus pelamis) fishery and seasonal temperature variability in the south-western Atlantic

The spatio‐temporal distribution of tuna fishing effort has been related to oceanographic circulation and features in several seas of the world. Understanding the relationship between environmental variables and fishery resource dynamics is important for management decisions and to improve fishery yields. The relationship between sea temperature variability and the pole‐and‐line skipjack tuna (Katsuwonus pelamis) fishery in the south‐western Atlantic Ocean was investigated in this work. Data from logbooks, satellite images (sea surface temperature), and oceanographic surveys were used in the analyses. Skipjack are caught in warm tropical waters of the Brazil Current (BC). The north–south displacement of fishing effort was strongly associated to seasonal variation of the surface temperature, which was coupled to the tropical BC flow. Oceanographic fronts from autumn to spring and a shallow thermocline in summer probably induces the aggregation of skipjack schools over the shelfbreak, favouring fishing operations. Hypotheses are proposed to explain the relationship between peaks of fishing events and the presence of topographic peculiarities of the shelfbreak.     

Understanding patterns of distribution shifts and range expansion/contraction for small yellow croaker (Larimichthys polyactis) in the Yellow Sea

Detecting and analyzing patterns of distribution shifts and range expansion/contraction is important to understand population dynamics and changes in stock status. Here, we develop a spatio‐temporal model for yellow croaker (Larimichthys polyactis), which was fitted to bottom trawl survey biomass data collected in the Yellow Sea in the winter of 2001–2017. The model accounts for both spatial and spatio‐temporal structure and can potentially include the effects of surface temperature and of an annual index, the Pacific Decadal Oscillation, represented using a recently developed spatially varying coefficient model. We selected a spatio‐temporal model with no covariates based on Akaike's information criterion. The center of gravity for yellow croaker was found to move northwest between 2001 and 2010, and then southwest over the period 2010–2017. These results reflected the predicted progressive disappearance of yellow croaker density hotspots (i.e., highest density areas) in the north and southeast areas of the Yellow Sea, which resulted in the central area of the Yellow Sea becoming the only yellow croaker density hotspot in 2017. This finding has important implications for fisheries management in the context of the China–South Korea fisheries agreement, as it indicates a measurable displacement of yellow croaker biomass toward China. The exclusion of covariates from the spatio‐temporal model was not expected a priori and may be due to the facts that environmental variations are not pronounced in winter in the Yellow Sea and that the representation of spatial and spatio‐temporal structure in spatio‐temporal models accounts for a large proportion of the variability in the data.     

Spatio‐temporal distribution of albacore (Thunnus alalunga) catches in the northeastern Atlantic: relationship with the thermal environment

When the spring seasonal warming starts, North Atlantic albacore (Thunnus alalunga) juveniles and pre‐adults perform a trophic migration to the northeastern Atlantic, to the Bay of Biscay and to the southeast of Ireland. During this migration, they are exploited by Spanish trolling and baitboat fleets. The present study analyzes the relationship between the albacore spatio‐temporal distribution and the thermal environment. For this approach, several analyses have been performed on a database including fishing logbooks and sea surface temperature (SST) images, covering the period between 1987 and 2003. SST values and the SST gradients at the catch locations have been statistically compared to broader surrounding areas to test whether the thermal environment determines the spatial distribution of albacore. General additive models (GAM) have been used also to evaluate the relative importance of environmental variables and fleet behaviour. The results obtained show that, although juvenile albacore catch locations are affected by fleet dynamics, there is a close spatial and temporal relationship with the seasonal evolution of a statistically significant preferential SST window (16–18°C). However, differences have been identified between the relationship of albacore with SST within the Bay of Biscay in July and August (higher temperature). Such differences are found also in the spatial distribution of the catch locations; these reflect clearly the presence of two groups, differentiated after the third week of the fishing campaign at the end of June. The analysis undertaken relating the distribution of North Atlantic albacore juveniles with thermal gradients did not provide any evidence of a relationship between these catch locations and the nearby occurrence of thermal gradients.     

Distribution patterns and population structure of the blue shark (Prionace glauca) in the Atlantic and Indian Oceans

The blue shark (Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheries from several nations in the Atlantic and Indian Oceans was compiled. Data sets included information on location, size and sex, in a total of 478,220 blue shark records collected between 1966 and 2014. Sizes ranged from 36 to 394 cm fork length. Considerable variability was observed in the size distribution by region and season in both oceans. Larger blue sharks tend to occur in equatorial and tropical regions, and smaller specimens in higher latitudes in temperate waters. Differences in sex ratios were also detected spatially and seasonally. Nursery areas in the Atlantic seem to occur in the temperate south‐east off South Africa and Namibia, in the south‐west off southern Brazil and Uruguay, and in the north‐east off the Iberian Peninsula and the Azores. Parturition may occur in the tropical north‐east off West Africa. In the Indian Ocean, nursery areas also seem to occur in temperate waters, especially in the south‐west Indian Ocean off South Africa, and in the south‐east off south‐western Australia. The distributional patterns presented in this study provide a better understanding of how blue sharks segregate by size and sex, spatially and temporally, and improve the scientific advice to help adopt more informed and efficient management and conservation measures for this cosmopolitan species.     

Spatio‐temporal analyses of marine predator diets from data‐rich and data‐limited systems

Accounting for variation in prey mortality and predator metabolic potential arising from spatial variation in consumption is an important task in ecology and resource management. However, there is no statistical method for processing stomach content data that accounts for fine‐scale spatio‐temporal structure while expanding individual stomach samples to population‐level estimates of predation. Therefore, we developed an approach that fits a spatio‐temporal model to both prey‐biomass‐per‐predator‐biomass data (i.e. the ratio of prey biomass in stomachs to predator weight) and predator biomass survey data, to predict “predator‐expanded‐stomach‐contents” (PESCs). PESC estimates can be used to visualize either the annual landscape of PESCs (spatio‐temporal variation), or can be aggregated across space to calculate annual variation in diet proportions (variation among prey items and among years). We demonstrated our approach in two contrasting scenarios: a data‐rich situation involving eastern Bering Sea (EBS) large‐size walleye pollock (Gadus chalcogrammus, Gadidae) for 1992–2015; and a data‐limited situation involving West Florida Shelf red grouper (Epinephelus morio, Epinephelidae) for 2011–2015. Large walleye pollock PESC was predicted to be higher in very warm years on the Middle Shelf of the EBS, where food is abundant. Red grouper PESC was variable in north‐western Florida waters, presumably due to spatio‐temporal variation in harmful algal bloom severity. Our approach can be employed to parameterize or validate diverse ecosystem models, and can serve to address many fundamental ecological questions, such as providing an improved understanding of how climate‐driven changes in spatial overlap between predator and prey distributions might influence predation pressure.     

2014年江苏省刺网渔业生产时空分布特征

基于抽样调查获得的2014年江苏省沿海刺网渔船生产数据,对江苏刺网渔业生产和渔获结构时空分布进行了初步分析。结果表明,江苏刺网渔船基本为本地近海生产,未出现远赴外地渔场生产情况;江苏中部以北近岸水域为刺网渔船主要作业渔场,而中部以南近岸水域少有渔船作业,可能是因为受航道、其它网具占用渔场、或捕捞对象分布习性等因素影响。伏季休渔前后在江苏中北部近岸水域,冬末春初在长江口渔场中部外侧水域,生产情况均相对较好,这可能与捕捞对象产卵、越冬行为相关。吕四渔场和大沙渔场是江苏刺网渔船主要作业水域,随着水温季节性变化,其生产范围会相应往北部和南部水域适当扩大;年初主要集中在吕四渔场,年末集中在大沙渔场;伏休前生产范围最广,伏休后生产范围有所收缩。另外,刺网捕捞主要渔获为价值较低的小个体鱼类和虾类,传统经济鱼类所占比例较低。由于刺网网目尺寸偏小,加上拖网、张网和多重刺网的泛滥使用,对渔业资源补充造成危害;刺网已经失去了传统上被认为是具有高度选择性的优良特征,建议管理部门重新考虑相关管理策略,开展针对各个渔业种群进行差别化精准管理研究。     

Distribution of whale shark (Rhincodon typus) off northern Peru based on habitat suitability

1. In the south‐eastern Pacific Ocean, few studies of whale sharks (Rhincodon typus) exist. In Peru, the northern coast has been identified as the area with the highest presence of whale sharks, yet their ecology in this area is poorly defined.
2. This study predicts the spatial distribution of whale sharks off coastal northern Peru (03°00′S–04°30′S) during La Niña and El Niño seasonal conditions, utilizing maximum entropy modelling. Between 2009 and 2018 (except for 2011), 347 whale sharks were geo‐referenced in northern Peru with greatest data recordings in the austral summer and spring during La Niña events.
3. Depth was the most important predictive variable for spatial distribution of whale sharks, followed by chlorophyll‐a. Sharks were predicted in shallower coastal waters in which chlorophyll‐a values are higher.
4. Habitat suitability was higher in the northern coastal part of the study area. Spring presents the most suitable environmental conditions for whale sharks, both during La Niña and El Niño conditions. The probability of whale shark presence in the north of Peru increases at higher chlorophyll‐a and sea surface temperature values. Therefore, whale sharks appear to aggregate seasonally in northern Peru, potentially exploiting rich foraging grounds.
5. In these areas of high suitability, whale sharks are susceptible to fisheries, bycatch, ship collisions, unmanaged tourism, and pollution; thus, management actions should focus in these areas.
6. This study represents a first step to understand the distribution and habitat suitability of whale shark in Peruvian waters. Further studies should identify suitable habitat for whale sharks in offshore areas. Also, these should focus on the connectivity of these aggregations with other localities in the south‐eastern Pacific in order to contribute to regional strategies for the conservation of this iconic species in this particular region.

     

Are circle hooks effective management measures in the pelagic longline fishery for sharks in the Gulf of Gabès?

1. This study evaluated the circle hook use as a tool for shark management in the pelagic longline fishery in the Gulf of Gabès.
2. The usual J‐hook No. 2 with 10° offset, which has been traditionally used by the fishery, was compared to the 18/0 non‐offset circle hook in an alternating fashion along the main line. In total, 22 experimental longline sets were deployed through the shark fishing seasons of 2016 and 2017 to examine the effects of hook types on the catch composition, the catch rates, the hooking location, and the status at haulback.
3. The catch composition differed significantly among hook types. Moreover, an overall increase in catch rates for the main species, the sandbar shark Carcharhinus plumbeus, and the shortfin mako shark Isurus oxyrinchus, was observed when using circle hooks.
4. There was no size‐selective effect of circle hooks for the common species. The circle hooks were not effective at reducing at‐haulback mortality of sandbar shark. Conversely, shortfin mako and smooth‐hound shark Mustelus mustelus showed significantly lower relative mortality at haulback with circle hooks than with J‐hooks. Furthermore, circle hooks were more frequently hooked externally than the J‐hooks for the three shark species.
5. Results demonstrated that the use of 18/0 non‐offset circle hooks in the pelagic shark longline fishery can reduce mortality at haulback for some species without any benefit for the dominant species, the sandbar shark.
6. Overall, it is difficult to promote the adoption of the use of circle hooks as a management measure in this specialized fishery. Management measures focusing on fishing effort controls, fishing closures in critical habitats, and size limits could have significant benefits for the conservation of shark species and may help to improve the sustainability of the shark fishery in the Gulf of Gabès.

     

基于空间自相关模型的南极半岛北部水域南极磷虾渔场时空演变特征

南极磷虾是南极海域生态系统的关键物种,是南极渔业的主要捕捞对象,其渔场具有显著的时空分布特征.为明晰南极半岛北部水域磷虾渔场的变动情况,本研究根据中国2010—2020年南极磷虾渔业统计资料,运用全局Moran's I指数和热点分析对该水域磷虾渔场的时空分布特征进行了分析.结果显示,南极半岛北部水域磷虾渔获量在空间分布...     

Forecast skill for predicting distribution shifts: A retrospective experiment for marine fishes in the Eastern Bering Sea

Forecasting distribution shifts under novel environmental conditions is a major task for ecologists and conservationists. Researchers forecast distribution shifts using several tools including: predicting from an empirical relationship between a summary of distribution (population centroid) and annual time series (“annual regression,” AR); or fitting a habitat‐envelope model to historical distribution and forecasting given predictions of future environmental conditions (“habitat envelope,” HE). However, surprisingly little research has estimated forecast skill by fitting to historical data, forecasting distribution shifts and comparing forecasts with subsequent observations of distribution shifts. I demonstrate the important role of retrospective skill testing by forecasting poleward movement over 1‐, 2‐ or 3‐year periods for 20 fish and crab species in the Eastern Bering Sea and comparing forecasts with observed shifts. I specifically introduce an alternative vector‐autoregressive spatio‐temporal (VAST) forecasting model, which can include species temperature responses, and compare skill for AR, HE and VAST forecasts. Results show that the HE forecast has 30%–43% greater variance than predicting that future distribution is identical to the estimated distribution in the final year (a “persistence” forecast). Meanwhile, the AR explains 2%–6% and VAST explains 8%–25% of variance in poleward movement, and both have better performance than a persistence forecast. HE and AR both generate forecast intervals that are too narrow, while VAST models with or without temperature have appropriate width for forecast intervals. Retrospective skill testing for more regions and taxa should be used as a test bed to guide future improvements in methods for forecasting distribution shifts.     

Abundance and distribution of the white shark in the Mediterranean Sea

Conservation of apex predators is a key challenge both in marine and terrestrial ecosystems. The white shark is a rare but persistent inhabitant of the Mediterranean Sea and it is currently assessed as “critically endangered” in the region. However, the population trends and dynamics of this species in the area are still unknown. Little is known about white shark distribution, habitat use and population abundance trends, aspects that are critical for conservation and management. In this study, we built the most comprehensive database of white shark occurrence records in the region. We collected 773 different records from different sources and used them to characterize the spatial and temporal patterns of abundance of Mediterranean white sharks between 1860 and 2016. We analysed these data by using generalized additive models and used spatially disaggregated information on human population abundance as a proxy of observation effort. Our results suggest a complex trajectory of population change characterized by a historical increase and a more recent reduction (61%, range 58%–72%) since the second half of the 20th century. In particular, analyses reveal a 52% (range 37%–88%) to 96% (range 92%–100%) overall decline in different Mediterranean sectors and a contraction in spatial distribution. Here, we provide the first reconstruction of abundance trends and offer new hypotheses regarding the drivers of change of white sharks in the Mediterranean. Our approach can be broadly applied to data‐poor contexts to reconstruct change and inform the conservation of endangered top predators in the Mediterranean Sea and other intensely used marine regions.     

Seasonal variability of cephalopod populations: a spatio‐temporal approach in the Western Mediterranean Sea

Cephalopod populations show wide temporal fluctuations in abundance, which have usually been investigated at inter‐annual scales related to environmental variability. However, cephalopods are also strongly linked to seasonal environmental fluctuations owing to their short life cycles and single seasonal breeding. Therefore, population abundance critically depends on the success of breeding and recruitment from the previous year and the optimization of resources in a narrow period of favorable conditions. This adaptation of population dynamics is paramount in marked oligotrophic systems, such as the western Mediterranean Sea. We used monthly landings per unit effort (LPUE) to explore the spatio‐temporal variability in seasonal patterns of three cephalopod species (Illex coindetii, Eledone cirrhosa and Octopus vulgaris). Common trends across the study area were characterized for each species. In all cases, seasonal patterns were geographically aggregated in relation to differences in local environment (i.e., primary production and surface hydro‐climatology). Variability in the mean seasonal pattern over time was also investigated under contrasting environmental or population regimes. The mean seasonal trend was more pronounced in regimes of high‐population densities, suggesting a density‐dependent control that can modify the strength of the environmental forcing in the seasonal patterns. Our study also evidences a spatial synchrony in the seasonal fluctuations of LPUEs. Scales of synchrony ranged from 70 to 200 km, indicating a patchy‐aggregated spatial pattern as a part of complex population structures in the western Mediterranean. Improving our understanding of seasonal dynamics of cephalopods across temporal and spatial scales may lead to improved forecasts and management strategies.     

大西洋中上层鲨鱼资源状况的初步探讨

据1994—2001年4个航次在金枪鱼延绳钓渔船对热带大洋性中上层鲨鱼资源进行调查，并分析国际大西洋金枪鱼资源保护委员会提供的关于中上层鲨鱼的渔业数据。结果表明：延绳钓渔业共兼捕13种鲨鱼，其中，尖吻鲭鲨和大青鲨是优势种类。尖吻鲭鲨在第1、第2和第4航次的CPUE分别为每千钩0．3502、0．1754和0．0642尾，呈下降趋势。大青鲨在第1～3航次的的CPUE达到每千钩5～7尾，而在第4航次下降为每千钩0．8尾。研究报告了中国金枪鱼船队自1993年开始在大西洋兼捕尖吻鲭鲨和大青鲨的渔获量，并根据捕捞死亡系数和大西洋总渔获量数据，初步探讨了尖吻鲭鲨和大青鲨年平均资源量，影响CPUE的因素和大西洋中上层资源状况。     

运用生产力-易捕率指数对10种热带太平洋鲨鱼种群的研究

热带太平洋是全球产量最高的金枪鱼渔场,大洋性鲨鱼种群遭受金枪鱼渔业的影响受到国际社会的高度关注。由于缺少渔业统计资料,一般难以运用标准的资源评估方法对这些兼捕的种类进行评估。笔者运用种群生产力-易捕率分析（productivity-susceptibility analysis,PSA）方法,对热带太平洋10种鲨鱼遭受金枪鱼延绳钓渔业影响的风险程度进行比较分析,并计算风险指数（vulnerability）。风险指数从低到高的种类依次为锤头双髻鲨（Sphyrna zygaena）、路氏双髻鲨（S.lewini）、无沟双髻鲨（S.mokarran）、尖吻鲭鲨（Isurus oxyrinchus）、狐形长尾鲨（Alopias vulpinus）、长鳍真鲨（Carcharhinus longimanus）、大青鲨（Prionace glauca）、镰状真鲨（C.falciformis）、浅海长尾鲨（A.pelagicus）、大眼长尾鲨（A.superciliosus）,表明大眼长尾鲨种群受延绳钓渔业影响而遭受过度捕捞的潜在风险最高,垂头双髻鲨的风险最低。该研究结果可以为热带太平洋金枪鱼延绳钓渔业的管理和生态系统保护提供科学参考。     

Distribution,body length,and abundance of blue shark and shortfin mako offshore of northeastern Japan,as determined from observed pelagic longline data, 2000–2014

Longline surveys have been conducted in the Northwest Pacific Ocean from 2000 to 2014 using chartered commercial longline vessels. Each year, two cruises were conducted offshore of northeastern Japan from mid‐April to mid‐June. For each longline set during the surveys, onboard scientists collected detailed biological information about the species caught, such as the size and sex, and recorded the catch numbers for all species. Blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus) have eurythermal distributions, but the application of a generalized additive model (GAM) showed that the sea surface temperatures (SSTs) at catch sites positive for shortfin mako were warmer than those for blue shark. On the basis of the GAM, the probabilities of occurrence of both sharks differed by size category: small sharks had a narrower SST range than that of large sharks. Most catches of both sharks were juveniles, and the nominal catch rate of blue shark was more than 10 times that of shortfin mako. The standardized catch per unit effort (CPUE) for both species was calculated using a generalized linear model (GLM) with negative binomial errors, or a delta‐lognormal GLM. The standardized CPUE for blue shark in the second quarter of the year peaked in the mid‐2000s and then decreased, but it has been increasing since 2012. The CPUE for shortfin mako in the second quarter generally increased, with fluctuations.     

江苏流刺网不同马力渔船作业的时空特征

本文基于抽样调查获得的2014全年江苏省沿海刺网渔船的生产数据,对江苏刺网不同马力渔船生产习惯,包括时间和空间上的选择特征,进行了初步研究。分析结果发现,不同马力渔船生产时间有一定差别,多数渔船主要生产时间均在伏季休渔结束后;小马力渔船不仅伏休后出航率较高,年底出航也保持较高水平。江苏刺网渔业整体生产有明显的季节特征,年初1—3月出航船数处于全年最低水平;清明节后、伏休前4—5月,出现一个生产小高潮;休渔结束后出航船数为全年最高水平。不同马力渔船空间分布不同,小马力渔船外海水域分布相对较少,随着马力增大渔船生产水域往外海和往北方向水域生产的可能性更大。不同月份渔船空间分布不同,1—3月生产处于偏北、偏近海水域; 4—5月生产偏向外海,相对前期南北方向变化不大、仍处于偏北水域; 8―9月偏近海和北部水域; 10—12月向南和外海移动进行生产。另外分析渔船的生产能力与马力之间的关系发现,渔船马力大小与单位捕捞努力量渔获量(CPUE)之间存在着正相关关系,关系式为CPUE=5.3428e~((0.0062′Power)),该结果可以为江苏刺网渔船捕捞强度的评估提供重要参考。最后基于研究结果,针对刺网渔船时间和空间上的生产特征提出了相应管理建议。     

Temperature effects on the blood oxygen affinity in sharks

In fish, regional endothermy (i.e., the capacity to significantly elevate tissue temperatures above ambient via vascular heat exchangers) in the red swimming muscles (RM) has evolved only in a few marine groups (e.g., sharks: Lamnidae, Alopiidae, and teleosts Scombridae). Within these taxa, several species have also been shown to share similar physiological adaptations to enhance oxygen delivery to the working tissues. Although the hemoglobin (Hb) of most fish has a decreased affinity for oxygen with an increase in temperature, some regionally endothermic teleosts (e.g., tunas) have evolved Hbs that have a very low or even an increased affinity for oxygen with an increase in temperature. For sharks, however, blood oxygen affinities remain largely unknown. We examined the effects of temperature on the blood oxygen affinity in two pelagic species (the regionally endothermic shortfin mako shark and the ectothermic blue shark) at 15, 20, and 25 °C, and two coastal ectothermic species (the leopard shark and brown smooth-hound shark) at 10, 15, and 20 °C. Relative to the effects of temperature on the blood oxygen affinity of ectothermic sharks (e.g., blue shark), shortfin mako shark blood was less affected by an increase in temperature, a scenario similar to that documented in some of the tunas. In the shortfin mako shark, this may act to prevent premature oxygen dissociation from Hb as the blood is warmed during its passage through vascular heat exchangers. Even though the shortfin mako shark and blue shark occupy a similar niche, the effects of temperature on blood oxygen affinity in the latter more closely resembled that of the blood in the two coastal shark species examined in this study. The only exception was a small, reverse temperature effect (an increase in blood oxygen affinity with temperature) observed during the warming of the leopard shark blood under simulated arterial conditions, a finding that is likely related to the estuarine ecology of this species. Taken together, we found species-specific differences in how temperature affects blood oxygen affinity in sharks, with some similarities between the regionally endothermic sharks and several regionally endothermic teleost fishes.     

Predicting overlap between drift gillnet fishing and leatherback turtle habitat in the California Current Ecosystem

Concern over bycatch of protected species has become a key factor in shaping fisheries management decisions. In 2001, the National Marine Fisheries Service established an annual closure of a large mesh drift gillnet fishery targeting swordfish from central Oregon to central California between August 15 and November 15 because of concerns of bycatch of endangered leatherback turtles (the Pacific Leatherback Conservation Area, PLCA). The spatio‐temporal constraints of the PLCA were developed to encompass nearly all previously observed leatherback turtle bycatch events in the fishery. The PLCA has been effective at reducing bycatch of leatherback turtles but has reduced fishing opportunities. In this study, we examined whether the timing of the current PLCA closure is optimal for leatherback turtle conservation, by developing statistical models of leatherback turtle presence inside the PLCA based on environmental variables. We also examined finer‐scale spatiotemporal patterns of potential overlap between the fishery and leatherback turtle foraging habitat using Maxent and Random Forests applied to logbook data and leatherback turtle telemetry data. Our results suggest that the temporal extent of the current static closure period is the shortest and most effective for protecting the turtles while allowing fishing during low bycatch‐risk periods. We also found that it is possible to predict foraging habitat of leatherback turtles and fishing effort using environmental variables. Identification of spatial and temporal hotspots of potential overlap between fishing effort and leatherback turtle distribution can form a basis for dynamic management approaches.     

Spatio‐temporal management of fisheries to reduce by‐catch and increase fishing selectivity

Time/area closures have been widely used in fisheries management to prevent overfishing and the destruction of marine biodiversity. To a lesser degree, such spatio‐temporal management measures have been used to reduce by‐catch of finfish or protected species. However, as ecosystem‐based management approaches are employed and more fisheries are managed through multispecies, multiobjective models, the management of by‐catch will likely become increasingly important. The elimination of by‐catch has become a primary goal of the fishing policies of many countries. It is particularly relevant in the United States, as the deadline for setting annual catch limits (ACLs) in all fisheries passes in 2011. This will result in a dramatic expansion of the number of catch and by‐catch quotas. Such catch measures may result in the early closure of otherwise sustainable fisheries when by‐catch quotas are exceeded. To prevent such closures and the consequent economic hardship to fishers and the economy, it is imperative that managers be given the tools necessary to reduce by‐catch and improve fishing selectivity. Targeted spatio‐temporal fishery closures are one solution open to managers. Here, we examine how the spatio‐temporal and oceanographic characteristics of by‐catch may be used by managers to design fishery closures, and place these methods within a decision tree to assist managers to identify appropriate management measures. We argue that the current movement towards marine spatial planning (MSP) presents an important impetus to examine how we manage fisheries spatially, and we offer a first step towards the objective participation of fisheries in the MSP process.