Targeting Abundant Fish Stocks while Avoiding Overfished Species: Video and Fishing Surveys to Inform Management after Long-Term Fishery Closures

Abstract

Historically, it has been difficult to balance conservation goals and yield objectives when managing multispecies fisheries that include stocks with various vulnerabilities to fishing. As managers try to maximize yield in mixed-stock fisheries, exploitation rates can lead to less productive stocks becoming overfished. In the late 1990s, population declines of several U.S. West Coast groundfish species caused the U.S. Pacific Fishery Management Council to create coast-wide fishery closures, known as Rockfish Conservation Areas, to rebuild overfished species. The fishery closures and other management measures successfully reduced fishing mortality of these species, but constrained fishing opportunities on abundant stocks. Restrictive regulations also caused the unintended consequence of reducing fishery-dependent data available to assess population status of fished species. As stocks rebuild, managers are faced with the challenge of increasing fishing opportunities while minimizing fishing mortality on rebuilding species. We designed a camera system to evaluate fishes in coastal habitats and used experimental gear and fishing techniques paired with video surveys to determine if abundant species could be caught in rocky habitats with minimal catches of co-occurring rebuilding species. We fished a total of 58 days and completed 741 sets with vertical hook-and-line fishing gear. We also conducted 299 video surveys in the same locations where fishing occurred. Comparison of fishing and stereo-video surveys indicated that fishermen could fish with modified hook-and-line gear to catch abundant species while limiting bycatch of rebuilding species. As populations of overfished species continue to recover along the U.S. West Coast, it is important to improve data collection, and video and fishing surveys may be key to assessing species that occur in rocky habitats.

Investigating three sources of bias in hook-and-line surveys: survey design, gear saturation, and multispecies interactions

“…For example, video surveys conducted at a subset of the California hookand-line survey sites provide information on site-specific species compositions and abundances that may explain trends in CPUE. Hook-and-line surveys sample a wide range of sizes (Millar and Fryer 1999;Starr et al 2016), although for certain species video surveys might observe both the smaller and larger fish than those captured using hook-and-line methods (Starr et al 2016). Indeed, hook-and-line gear selectivity has been estimated to be domeshaped (Garner et al 2014), although this varies by species and hook size.…”

The area–heterogeneity tradeoff applied to spatial protection of rockfish (Sebastes spp.) species richness

“…Circles are bivariate raw data with random jitter rockfish and other benthic fishes, reducing abundance and truncating size and age structure, which affects per capita fecundity (Hixon, Johnson, & Sogard, 2014). Well-situated MPAs with adequate monitoring and compliance can protect corals and glass sponges (Huvenne, Bett, Masson, Le Bas, & Wheeler, 2016) and promote rockfish recovery and persistence, although benefits for species with slow life histories may require decades to manifest (Starr et al, 2016).…”

A comparison of length distributions of rockfishes (Sebastes spp.) from submersible and trawl surveys off central California

“…A number of studies have compared other aspects of data collected during underwater visual surveys and trawl surveys of rockfishes, including fish density on trawlable habitat (Adams et al, 1995), trawl catch efficiency (Krieger, 1993), fish frequency of occurrence and weights on trawlable and untrawlable habitat (Starr et al, 2016), and species composition and densities on trawled and untrawlable habitat (Jagielo et al, 2003). Lauth et al (2004) estimated size-specific selectivity for a trawl survey of thornyheads (Sebastolobus spp.)…”

“…Since 1999, several rockfish species have recovered from an overfished to a rebuilt status; currently, 2 species remain classified as overfished and in rebuilding status (cowcod [S. levis]; and yelloweye rockfish [S. ruberrimus]). However, regulatory measures implemented to reduce fishing mortality for rebuilding rockfish stocks have also reduced the amount of fishery-dependent data available for stock assessments (Field et al, 2006;Starr et al, 2016). A principal source of fisheryindependent data for rockfish stock assessments is the Northwest Fisheries Science Center (NWFSC) West Coast Bottom Trawl Survey (hereafter referred to as the trawl survey; Keller et al, 2017), which cannot be conducted in complex rocky habitats where the highest densities of most deep-water rockfishes occur.…”