BACKGROUND Approximately 83% of British Columbia’s continental shelf and slope is affected by human activity with only ~5% off–limits to commercial activities. This region is home to Canada’s most threatened group of marine finfish - the rockfish (Sebastes spp.). Seven of the 38 rockfish species found in coastal BC waters are listed by COSEWIC (the status of many others is data deficient). Life-history characteristics such as extreme longevity, slow growth, relatively large size, old age at maturity, localized movement patterns and poor post-catch survival combine to make inshore rockfish extremely susceptible to overfishing. In 2007 the Department of Fisheries and Oceans established 164 Rockfish Conservation Areas (RCAs); marine reserves where gear restrictions are imposed on both recreational and commercial harvest intended to reduce or eliminate rockfish harvest.
Evaluation of RCA efficacy, and marine reserves in general, in meeting conservation objectives has yielded mixed results. Much of the confusion is explained by varying “objectives” of marine reserves. Recent research suggests conservation benefits are typically limited to species otherwise targeted for harvest and do not, contrary to popular perception, often yield broader biodiversity conservation benefits. When conservation objectives are explicitly limited to targeted species (i.e. RCAs), efficacy is more easily demonstrated though there is far from consensus among researchers regarding reserve efficacy even in this narrow context. Much of the debate is rooted in the logistical challenges of working in sub-surface marine habitats. The severe constraints inherent to this environment severely limit accuracy and precision of organism detection. Simply stated, different observation methods yield significantly different results making the performance estimates of RCAs equivocal. The magnitude of this issue has risen sharply with the proliferation of underwater video (UWV) technology as a survey and research tool. Differential strengths and weaknesses of conventional direct diver visual observations vs. observations on video (baited and unbaited; towed and stationary) presents a constant risk of methodologically-driven bias skewing results. Despite very significant investment in RCAs as the main (arguably only) significant conservation tool for endangered rockfish, efficacy remains unknown due to methodologically induced biases. This project seeks to resolve this dilemma.
The video below shows a quillback rockfish (Sebastes maliger) Below a Pacific halibut (Hippoglossus stenolepis) searches filling the camera while a pair of spotted ratfish for the source of the bait in front of the camera. (Hydrolagus colliei) investigate the bait in the background.
Graduate Student Lily Burke (L) and research tech Darienne Lancaster (MA) on the aft deck of Jolly Seber off Galiano Island
Success of any marine reserve is directly linked to compliance of harvesters in observing restrictions. Species-specific reserves such as RCAs are situated so as to encompass high quality habitat and operate on the assumption of “spillover”, or emigration of individuals beyond the boundaries of the reserve to areas of lower density. Thus the highest density of a targeted species is typically inside a reserve posing significant motivation to ignore reserve restrictions. Not surprisingly, lack of enforcement of reserve boundaries and/or gear restrictions is among the most common reason for reserve failure. In BC chronic and escalating federal and provincial funding cuts have greatly diminished on-the-water enforcement of RCAs and non-compliance is a potentially powerful variable in explaining differential RCA efficacy.
In 2013 Env Studies colleague Dr. Natalie Ban and MA student Darienne Lancaster characterized the level of fisher compliance in Southern Gulf Island RCAs. They used shore-mounted “camera traps” to quantify RCA non-compliance. Results suggest the compliance is generally quite low. Thus, this project leverages the work of Ban and Lancaster by incorporating compliance as an explanatory variable in RCA efficacy for the first time. Working closely with, and with generous support from, the Canadian Wildlife Federation and the Galiano Conservancy Association (with additional support from MEOPAR & CFI), we test for survey methodological biases while surveying fish populations inside and outside RCAs across a gradient of compliance to quantify if and how RCAs achieve conservation benefits while asking what magnitude of noncompliance is necessary to eliminate the benefit an RCA might otherwise provide?
Our work is concentrated in the RCAs of the Southern Gulf Islands region, between Victoria and Vancouver British Columbia with many sites near Galiano Island. Target RCA sites are chosen via a randomized selection process first, followed by identification of matched reference sites located 100-1000m from the RCA boundary. Reference sites are identified using ArcGIS and other digital bathymetric resources and match as closely as possible the relevant physical habitat features present in the paired RCA. A two-person SCUBA team conducts multiple 30m transects in both the RCA and paired reference site collecting abundance and diversity data of all finfish observed. Following the SCUBA surveys the baited underwater video system is deployed for 30 min at a randomly selected point along the SCUBA transects (below left). The procedure is repeated at all sites which in the cumulative, cover the gradient of compliance (below right). In follow-up research at a subset of survey sites, a towed camera array will also deployed, allowing a tripartite examination methodological complimentary - SCUBA, baited stationary camera, unbaited towed camera.
Graphic representation of experimental design at paired RCA and reference sites.
A broader view of the experimental design with inclusion of the angler compliance gradient across RCA and reference sites.