Evolution of operational management procedures for the South African West Coast rock lobster (Jasus lalandii) fishery

Abstract

The commercial fishery for Jasus lalandii, the South Africa West Coast rock lobster, began in the late 1800s and at its peak in the early 1950s yielded an annual catch of 18 000 t. Although this annual catch has dropped to only some 2000 t over recent years, the fishery remains South Africa's third most valuable for landed value. The primary reason for the low total allowable catch (TAC) over these recent years has been a marked drop in somatic growth rate that occurred at the end of the 1980s, for reasons that remain unexplained. A key problem in formulating TAC recommendations with longerterm objectives in mind, has been uncertainties about likely future trends, particularly in somatic growth and recruitment. To address this problem, an "operational management procedure" (OMP) was adopted in 1997 and has twice been re-evaluated and modified (in 2000 and 2003) in the light of further data and changing perceptions of resource dynamics. The history of this process is reviewed, concentrating on the most recent modification. In particular, a summary is given of the process by which the merits of alternative management procedures were evaluated over a range of important uncertainties about the dynamics of the resource. This summary includes a discussion of the key trade-offs between resource rebuilding, future TAC trends and TAC variability, and the eventual choice that was made. M04015; Online publication date 8 June 2005 Received 8 February 2004; accepted 4 November 2004The paper concludes by listing a number of lessons learnt concerning best practice for OMP development as this process evolved.

Management strategy evaluation for rock lobster,Jasus edwardsii, off Victoria, Australia: Accounting for uncertainty in stock structure

“…Management strategies have been evaluated for many fisheries and, in recent years, for ecosystem objectives (e.g., Fulton et al 2007;Dichmont et al 2008). In particular, they have been evaluated (and implemented) for several species of rock lobster Breen et al 2003;Johnston & Butterworth 2005). The advantages of the MSE approach include: (1) uncertainty in the entire management system (including process, observation, model, estimation and implementation uncertainty- Francis & Shotton (1997)) can be taken into account; (2) finding a management strategy that is robust to uncertainty rather than a management strategy that performs optimally if reality is known; (3) development of management strategies leads to the specification of management objectives using quantifiable performance measures; and (4) the nature of the evaluation forces consideration of a longer-term view of the exploitation of the resource.…”

“…1997), "managementprocedures" , "operational management procedures" (Johnston & Butterworth 2005), "harvest algorithms" (Cooke 1999), and "harvest control rules" (Kell et al 1999) are "fully-specified feedback control systems applied as a part of a fishery management system" (McAllister et al 1999). A management strategy therefore includes specifications related to: (1) what data will be collected; (2) how those data will be processed; (3) what estimates will be made from the data; and (4) how those estimates will be used to determine management actions .…”

An ecosystem approach to fisheries in the southern Benguela context

“…Recent assessments estimate the exploitable biomass (lobsters >75 mm carapace length [CL]) of the species to be around 10% of its pristine value, with spawning biomass (females >65 mm CL) estimated at around 21% (Johnston 1998). The large reduction in biomass is likely to have had a substantial impact on the ecosystem.…”

Modeling a Regime Shift in a Kelp Forest Ecosystem Caused by a Lobster Range Expansion

“…Rock Lobster.-The West Coast rock-lobster stock assessment uses a detailed size-structured model (Johnston and Butterworth 2005) to generate an annual recommended total allowable catch Butterworth 2005, Butterworth 2008). A size-structured approach was used, but size data can be converted into age data on the basis of the growth rate of lobsters derived from annual tagging, and a length-at-age matrix calculated (Johnston and Butterworth 2001).…”