The assessment of fishery status depends on fish habitats

Abstract

At the crux of the debate over the global sustainability of fisheries is what society must do to prevent over‐exploitation and aid recovery of fisheries that have historically been over‐exploited. The focus of debates has been on controlling fishing pressure, and assessments have not considered that stock production may be affected by changes in fish habitat. Fish habitats are being modified by climate change, built infrastructure, destructive fishing practices and pollution. We conceptualize how the classification of stock status can be biased by habitat change. Habitat loss and degradation can result in either overly optimistic or overly conservative assessment of stock status. The classification of stock status depends on how habitat affects fish demography and what reference points management uses to assess status. Nearly half of the 418 stocks in a global stock assessment database use seagrass, mangroves, coral reefs and macroalgae habitats that have well‐documented trends. There is also considerable circumstantial evidence that habitat change has contributed to over‐exploitation or enhanced production of data‐poor fisheries, like inland and subsistence fisheries. Globally many habitats are in decline, so the role of habitat should be considered when assessing the global status of fisheries. New methods and global databases of habitat trends and use of habitats by fishery species are required to properly attribute causes of decline in fisheries and are likely to raise the profile of habitat protection as an important complementary aim for fisheries management.

Migration and Residency of Sandbar, Atlantic Sharpnose, Bull, and Nurse Sharks in the Northern Gulf of Mexico

“…Although there has been an extensive effort for defining essential fish habitat for several shark species (NMFS 2017), specific habitat types and their importance were not generally incorporated into stock assessments for the most part (SEDAR 2006(SEDAR , 2013(SEDAR , 2017. However, as Brown et al (2019) have extensively discussed, this lack of habitat evaluation needs to be addressed and the importance of site fidelity and movement patterns in relation to specific habitats are critical in fishery management.…”

Substrate type and brightness preference ofSchizothorax wangchiachiiandPercocypris pingijuveniles

“…Habitat substrates provide foraging, predator avoidance and spawning sites for fish, and the characteristics of substrates are often regarded as highly important indicators of habitat condition (Brown et al, 2019;Cushing, Bain, & Stevenson, 2000;Zhang et al, 2017).…”

Dependency of Queensland and the Great Barrier Reef’s tropical fisheries on reef-associated fish

“…A stock assessment to revise the total allowable catch for reef fisheries would need quantitative estimates linking reef habitat loss to stock productivity parameters 12,46 . Current stock assessments have identified this knowledge gap as a major limitation 46 .…”

“…Fish habitat associations. Fish-habitat associations were first assembled from the global Fishscape database (Brown et al 2019, available at https ://www.seasc apemo dels.org/fishs cape/). Additional information focussing on Queensland species was added through a targeted review of published literature.…”

“…We quantified the risk of reef habitat loss as the probability that current catch would exceed MSY given a sudden reduction in the intrinsic growth parameter (r). A decline in the intrinsic growth is representative of the loss of reef habitat, because reef habitat supports recruitment of reef species 12 . We varied the per cent reduction in the intrinsic growth from 0 to 100% in 1% increments, then calculated the probability that the average of catches from 2016 to 2018 would exceed the MSY.…”