Developing stock assessment models of sea cucumber fisheries and assessing their population status 

Sea cucumber fisheries are susceptible to rapid overexploitation due to their ease of capture, their reef level demographics, and low rates of population productivity. As a result, many circumglobal examples exist of collapsed sea cucumber stocks. The driving factor behind their overexploitation is demand from the Chinese seafood market where bêche de mer (the market name for dried sea cucumber) is sold for hundreds of USD per kilo. There is a pressing need for stock assessments to provide a scientific basis for management advice for the bêche de mer fisheries. However, sea cucumbers cannot be aged, measured, or weighed, making sea cucumbers one of the most difficult taxa to assess. While this paints a depressing picture of the global landscape, there are regional bright spots where sea cucumber fishing is sustainably managed. One such example is the Queensland Sea Cucumber Fishery which operates on the Great Barrier Reef. The fishery has many management measures including rotational harvest zones, daily effort limits, size limits and total allowable catches, making this one of the most extensively managed sea cucumber fisheries in the world. Despite this, stock assessments remained lacking for the fishery preventing the efficacy of these management measures from being fully assessed.

A now completed project, addressed this by developing two different stock assessment models and applying them to four target species, composing six stocks. These models relied on surveys which estimated biomass in primary fishing grounds and used this information to anchor the models estimated population size to a specific point in time. Knowledge of fishery catches, catch per unit effort and selectivity allowed the relative biomass to be estimated and demonstrated that these species had been fished sustainably through relatively light exploitation. Continuing work is examining the lessons learned from this fishery and its recently completed stock assessments. There are few successfully applied stock assessment models for sea cucumbers, providing an opportunity for this research to be extended to fisheries in need of scientific advice.

Specific aims of the project include:

• Develop stock assessment models for several sea cucumber species fished on the GBR.

• Assess the population status of these species.
• Provide management advice to ensure future fishing is sustainable. 
• Highlight the lessons learned from these assessments and their applications to other fisheries.​