The assessment of fishery status depends on the condition of fish habitats

Abstract

At the crux of the debate over the global sustainability of fisheries is what society must do prevent overexploitation of fisheries and aid recovery of fisheries that have historically been overexploited. 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 conceptualise how the classification of stock status can be biased by habitat change. Habitat loss 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 overexploitation 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 the causes of decline in fisheries, and are likely to raise the profile of habitat protection as an important complementary aim for fisheries management.

Macroalgal meadow habitats support fish and fisheries in diverse tropical seascapes

“…Tropical macroalgal habitats likely play several roles in supporting local fisheries production. First, as with kelp forests (see Bertocci et al, 2015; Brown et al, 2018), macroalgal production may enhance fishable biomass through direct consumption by browsing herbivores (e.g. Spinytooth parrotfish, Calotomus spinidens , Labridae; Marbled parrotfish; and some Siganus species; Fox & Bellwood, 2008; Hoey, Brandl, & Bellwood, 2013; Unsworth, Taylor, Powell, Bell, & Smith, 2007; Table 1).…”

“…The potential for tropical macroalgal habitat to be fish nurseries, trophic facilitators, and corridors for fish movement between habitats suggest they warrant the same recognition as mangroves, seagrass beds and coral reefs in ecosystem‐based fisheries management. Spatial management and monitoring of tropical macroalgal habitats could then provide capacity for the adaptive management of habitat‐based fluctuations in fishable biomass of coastal target species (Brown et al, 2018; Green et al, 2014). This will require more quantitative information on the key aspects of macroalgal habitat quality and connectivity that affect both standing fish biomass and recruitment, and how these habitat traits respond to climatic cycles and disturbance events (Aburto‐Oropeza et al, 2007; Wilson et al, 2017, 2018).…”

“…Characterization of a fauna according to surveys within a single habitat type, therefore, can lead to a conclusion that a collection of species are dependent on that habitat type. A wider seascape perspective that tracks the abundance and activities of fishes across different patch habitat types is needed to reveal the full suite of connected habitats that sustain fish populations and communities (Brown et al, 2018; Olds et al, 2018; Sambrook et al, 2019).…”