Development of an individual-based tag recapture model to benchmark biomass and harvest rates in an iconic lobster fishery

The West Coast Rock Lobster Managed Fishery (WCRLMF) moved from input to output controls in 2010. This change affected the relativity of fishery-based data sources (e.g., catch rates and landed size composition), making the assessment of the fishery problematic. A novel examination of the stock dynamics was required to ensure the robustness of the stock assessment and associated management arrangements. This study derived estimates of current biomass levels and harvest rates from the release of over 60,000 tagged western rock lobsters (Panulirus cygnus). A Brownie tag-recapture (BTR) model was initially implemented to provide an assessment on a fishery-wide basis. Estimates from this were compared to those derived from a novel purpose-built tag-recapture individual-based model (IBM) that accounted for sex, size, month, and location-specific changes in catchability. The two models produced similar estimates on a fishery-wide scale—harvest rate (HR 0.26 vs 0.30, respectively) and legal-sized biomass (about 24,500 vs 20,735 t, respectively)—while the IBM also provided estimates on a far finer spatial and temporal scale. Both models indicate that the WCRLMF is currently in a very sustainable condition and is being fished at a rate below maximum economic yield (HRmey is about 0.39). These findings were in concert with estimates derived for this fishery based on two separate catch-rate based population models, an integrated population model and a biomass-dynamics model. Such strong agreement among all models provides great certainty in the current assessment and management of this important marine resource

Assessing possible environmental causes behind the reduced colonisation of western rock lobster puerulus collectors by a wide suite of species. FRDC report : project 2008/085

Objectives 1) Begin monitoring the community composition of marine flora and fauna along the Western Australian coastline during this current poor settlement period. 2) Develop standard methodology for monitoring the spatial and temporal variability in the settlement of marine flora and fauna. 3) Determine what environmental parameters may be linked to the majority of variation in the floral and faunal communities colonizing puerulus collectors, focusing on those relating to puerulus settlement. 4) Identify indicator marine flora and fauna species for monitoring the influences of environmental change on Western Australian marine environment. 5) Detect any known or potential introduced marine pests within the Western Australian environment

Development of an industry-based habitat mapping/monitoring system FRDC Project No 2011/021

Mapping / monitoring in the marine environment can be a very costly exercise. Scientists from the Department of Primary Industries and Regional Development; Fisheries Division (FD) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) have developed a small, low-cost automated camera system that, when fitted to commercial fishing gear, can achieve this at minimal cost. The POTBot (Pictures Of The Bottom) system is a cheap, small “smart” camera that can track its position globally and the date and time, and can record high-definition video and water temperature readings when it determines it has been deployed into the ocean

Evaluating the potential use of change-in-ratio and index removal techniques for determining harvest rates and efficiency increases in the Western Rock Lobster Fishery FRDC Project 2009/019

Objectives: 1. Assess current data sources and their potential for estimating harvest rates and increases in efficiency in the western rock lobster fishery using change in ratio and index removal techniques. 2. Evaluate whether additional sources of information are needed to produce more robust estimates of harvest rate and efficiency increase. 3. Assess whether the estimates of harvest rate and fishing efficiency are reliable and could be used for the management of the western rock lobster fishery

Decision-support tools for economic optimization of Western Rock Lobster fishery

Objectives: 1. To estimate the annual catch and effort to achieve optimum economic yield 2. To evaluate intra-annual market-based management strategies. 3. To evaluate the economic effect of current and proposed management changes

Changes in egg production of the western rock lobster (Panulirus cygnus) associated with appendage damage

Data collected during fish-ery-independent sampling programs were used to examine the impact of appendage damage (indicated by lost or regenerated legs and antennae) on the reproductive output of female western rock lobster (Panulirus cygnus). Most of the damaged females sampled had one (53%), two (27%), or three (13%) appendages that had been lost or that were regenerating. Appendage damage was associated with the reduced probability of a female developing ovigerous setae; and if setae were produced, with the reduced probability that females would produce more than one batch of eggs within a season. These effects were more pronounced as the number of damaged appendages increased. From data collected in 2002, it was estimated that the total number of eggs produced by mature females caught in the fishery was significantly reduced (P<0.001) by 3–9% when the impact of appendage damage was included

Status of the Cockburn Sound Crab Fishery

Blue swimmer crabs (Portunus armatus) (formerly Portunus pelagicus; Lai et al., 2010) in Cockburn Sound, Western Australia, are the basis of an important commercial and recreational fishery close to the Perth metropolitan area with the commercial fishery achieving a peak catch of 362 t in 1997/98 and a recreational catch of about 18 t. Commercial blue swimmer crab catches declined significantly since 2000 due to low stock abundance, resulting in the closure of the fishery in December 2006

Summary of the West Coast Rock Lobster Managed Fishery science and modelling review

An independent peer review of the science and modelling associated with the West Coast Rock Lobster Managed Fishery was undertaken in May/June 2018. The impetus behind this review was two-fold, i) to address industry concerns that stock assessment modelling was not reflecting what was being experienced by fishers on-water, and ii) to increase stakeholders understanding of, and confidence in, the stock assessment process while ensuring that the process was commensurate with contemporary scientific practices

Stock Assessment for the West Coast Rock Lobster Fishery

The recreational component of the western rock lobster fishery is managed under fisheries regulations that impose a mix of input and output controls on individual recreational fishers. These arrangements are designed to complement the management plan for the commercial fisher

Evaluating source-sink relationships of the western rock lobster fishery using oceanographic modelling: Final FRDC Report – Project 2008/087

Objectives 1. To determine the relative contribution of larval production from different areas to the abundance and spatial distribution of puerulus settlement over 15 years using a larval advection mode