Methods for Identifying Species Complexes Using a Novel Suite of Multivariate Approaches and Multiple Data Sources: A Case Study With Gulf of Alaska Rockfish

Abstract

International and national laws governing the management of living marine resources generally require specification of harvest limits. To assist with the management of data-limited species, stocks are often grouped into complexes and assessed and managed as a single unit. The species that comprise a complex should have similar life history, susceptibility to the fishing gear, and spatial distribution, such that common management measures will likely lead to sustainable harvest of all species in the complex. However, forming complexes to meet these standards is difficult due to the lack of basic biological or fisheries data to inform estimates of biological vulnerability and fishery susceptibility. A variety of cluster and ordination techniques are applied to bycatch rockfish species in the Gulf of Alaska (GOA) as a case study to demonstrate how groupings may differ based on the multivariate techniques used and the availability and reliability of life history, fishery independent survey, and fishery catch data. For GOA rockfish, our results demonstrate that fishing gear primarily defined differences in species composition, and we suggest that these species be grouped by susceptibility to the main fishing gears while monitoring those species with high vulnerabilities to overfishing. Current GOA rockfish complex delineations (i.e., Other Rockfish and Demersal Shelf Rockfish) are consistent with the results of this study, but should be expanded across the entire GOA. Differences observed across species groupings for the variety of data types and multivariate approaches utilized demonstrate the importance of exploring a diversity of methods. As best practice in identifying species complexes, we suggest using a productivity-susceptibility analysis or expert judgment to begin groupings. Then a variety of multivariate techniques and data sources should be used to identify complexes, while balancing an appropriate number of manageable groups. Thus, optimal species complex groupings should be determined by commonality and consistency among a variety of multivariate methods and datasets.

Editorial: Data-limited research in stock assessment to increase the understanding of fisheries resources and inform and improve management efforts

“…Source: www.scopus.com. Mannini et al, 2020;Omori et al, 2021;Rudd al., 2021;Sańchez-Maroño et al, 2021).…”

Oceans of plenty? Challenges, advancements, and future directions for the provision of evidence-based fisheries management advice

“…The species selected, however, should generally have higher risk levels (i.e., be more vulnerable to external pressures) compared to the other non-indicator species (Landres et al 1988 ; Newman et al 2018 ). Conversely, monitoring and assessing a stock complex relies on appropriately assigning stocks to a complex assuming that grouped species will have similar life history traits and functional responses to ecosystem and anthropogenic perturbations (e.g., Cope et al 2011 ; Omori et al 2021 ). As the trend towards ecosystem-based fisheries management (EBFM) continues, increased emphasis will be placed on simultaneously managing across species, which should aid in developing management advice that transcends technical interactions across multiple species (Fulton et al 2019 ).…”