Marine reserves solve an important bycatch problem in fisheries

Abstract

Management of the diverse fisheries of the world has had mixed success. While managing single species in data-rich environments has been largely effective, perhaps the greatest challenge facing fishery managers is how to deal with mixed stocks of fish with a range of life histories that reside in the same location. Because many fishing gears are nonselective, and the costs of making gear selective can be high, a particular problem is bycatch of weak stocks. This problem is most severe when the weak stock is longlived and has low fecundity and thus requires a very long recovery time once overfished. We investigate the role that marine reserves might play in solving this challenging and ubiquitous problem in ecosystem-based management. Evidence for marine reserves' potential to manage fisheries in an ecosystem context has been mixed, so we develop a heuristic strategic mathematical model to obtain general conclusions about the merits of managing multispecies fisheries by using reserves relative to managing them with nonspatial approaches. We show that for many fisheries, yields of strong stocks can be increased, and persistence of weak stocks can be ensured, by using marine reserves rather than by using traditional nonspatial approaches alone. Thus, reserves have a distinct advantage as a management tool in many of the most critical multispecies settings. We also show how the West Coast groundfish fishery of the United States meets these conditions, suggesting that management by reserves may be a superior option in that case.fishery management | marine protected area | weak stocks | bycatch F isheries management has a mixed record of success in the sea (1-3). Despite many successes (4, 5), failures are common and reflect limitations of science, policy, and management. Arguably, the biggest scientific failure is the continued reliance on single-species models in situations, when more ecosystembased approaches are warranted (1, 2, 6). Although management decisions are often based on one target species, most fisheries simultaneously impact the dynamics of other secondary targets, or bycatch. If sustainable catch rates differ across these species, optimal decisions for one species may have disastrous effects for others; these are "weak stocks" that are driven to unsustainably low levels when fishing is optimized for the target species. Although this problem has been well known for 50 y or more (7), it remains one of the most pressing challenges in fisheries, and weak stock disasters are becoming more commonplace (8). The traditional approach for dealing with this problem is to reduce the catch rates of all species to ensure persistence of the weak stock; this often entails severe cutbacks in the harvest of target species. Examples include nearly all groundfish fisheries on the west and east coasts of North America (8).Given the nature of the problem, an approach based on strategic rather than detailed models is an important step. We specifically model a situation where there is a target species that is the focus of ec...

Estimating the economic benefits and costs of highly‐protected marine protected areas

“…Where sustainable catch rates differ across species, leading to strong and weak stocks, MPAs may also benefit fisheries by reducing the cost of bycatch reduction (Hastings et al. ). Generally, economic benefits to fisheries are experienced as increased revenue per unit of fishing effort, or reduced effort and cost per unit of fish caught.…”

“…Whether MPAs provide benefits to fisheries will depend on a range of features, including (1) source-sink dynamics of the fish population, (2) size of an MPA relative to the home range of fish species (Ovando et al 2016), (3) geographic extent of the fish population, (4) status of the fishery prior to MPA implementation (Ovando et al 2016), and most importantly, (5) adequate management and enforcement. Where sustainable catch rates differ across species, leading to strong and weak stocks, MPAs may also benefit fisheries by reducing the cost of bycatch reduction (Hastings et al 2017). Generally, economic benefits to fisheries are experienced as increased revenue per unit of fishing effort, or reduced effort and cost per unit of fish caught.…”

“…), and fisheries (Hastings et al. ). First, we briefly summarize how the benefits that MPAs may provide can be estimated in economic terms, and the challenges involved in obtaining these estimates (Fig.…”

“…In the process, we discuss a number of methodological options and consider the relevance and potential benefits from using economic information. We have focused our discussion on highly-protected MPAs as these have documented ecological benefits across a range of taxa , ecosystems (Bates et al 2014), and fisheries (Hastings et al 2017). First, we briefly summarize how the benefits that MPAs may provide can be estimated in economic terms, and the challenges involved in obtaining these estimates ( Fig.…”

Modelling habitat use by the Guiana dolphin, Sotalia guianensis, in south‐eastern Brazil: Effects of environmental and anthropogenic variables, and the adequacy of current management measures

“…Despite the overlap, at least partial, between the distributions of many marine species and MPAs, numerous illegal human activities continue within these areas and impact their biodiversity. Recent studies have found that no‐take zones, such as Marine Reserves, are effective management tools, which can provide valuable conservation and socio‐economic benefits by preventing habitat destruction and reducing fishing pressure, thus allowing the biomass and diversity of these areas to increase (Baskett & Barnett, ; Evans & Russ, ; Hastings, Gaines, & Costello, ; Pichegru, Grémillet, Crawford, & Ryan, ).…”