Effects of Management Tactics on Meeting Conservation Objectives for Western North American Groundfish Fisheries

Abstract

There is considerable variability in the status of fish populations around the world and a poor understanding of how specific management characteristics affect populations. Overfishing is a major problem in many fisheries, but in some regions the recent tendency has been to exploit stocks at levels below their maximum sustainable yield. In Western North American groundfish fisheries, the status of individual stocks and management systems among regions are highly variable. In this paper, we show the current status of groundfish stocks from Alaska, British Columbia, and the U.S. West Coast, and quantify the influence on stock status of six management tactics often hypothesized to affect groundfish. These tactics are: the use of harvest control rules with estimated biological reference points; seasonal closures; marine reserves; bycatch constraints; individual quotas (i.e., ‘catch shares’); and gear type. Despite the high commercial value of many groundfish and consequent incentives for maintaining stocks at their most productive levels, most stocks were managed extremely conservatively, with current exploitation rates at only 40% of management targets and biomass 33% above target biomass on average. Catches rarely exceeded TACs but on occasion were far below TACs (mean catch:TAC ratio of 57%); approximately $150 million of potential landed value was foregone annually by underutilizing TACs. The use of individual quotas, marine reserves, and harvest control rules with estimated limit reference points had little overall effect on stock status. More valuable fisheries were maintained closer to management targets and were less variable over time than stocks with lower catches or ex-vessel prices. Together these results suggest there is no single effective management measure for meeting conservation objectives; if scientifically established quotas are set and enforced, a variety of means can be used to ensure that exploitation rates and biomass levels are near to or more conservative than management targets.

Which design elements of individual quota fisheries help to achieve management objectives?

“…; Melnychuk et al . ). They allow for nonlinear relationships between a predictor and response variable, make no parametric assumptions about the response variable, can handle missing values of predictors and are less susceptible to over‐fitting compared with parametric methods such as generalized linear models because the number of predictors available for selection at any given node of a tree is limited to a specified number.…”

Effects of biological, economic and management factors on tuna and billfish stock status

“…This approach was used previously to analyse similar data (Melnychuk et al . ) and has been increasingly used in ecology and fisheries studies (Lennert‐Cody and Berk ; Gutiérrez et al . ).…”

“…Exploitation history is an important factor affecting the conservation status of many exploited stocks (Melnychuk et al . ; Neubauer et al . ) including tuna species.…”

California's Commercial Fisheries: 1981-2012

“…An important consideration is fi nding an acceptable balance between effi ciency gains and employment losses. Management measures often involve such trade-offs; there is rarely a universally "best" way to achieve any given management objective (Melnychuk et al, 2013).…”

“…For instance, PFMC groundfi sh management includes a complex mix of harvest, effort, area, season, and gear regulations that constrain target species catches (in some cases to levels well below maximum sustainable yield) to minimize bycatch of overfi shed stocks that comingle with targeted stocks on the fi shing grounds (Hilborn et al, 2011;Melnychuk et al, 2013). The PFMC has also implemented habitat protection measures, including closure of essential fi sh habitat to trawling (PFMC, 1998b).…”