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Crystal Crab is a deep water (> 400 m) crab species which is commercially caught off the west (West Coast Deep Sea Crab Managed Fishery: WCDSC) and south (South Coast Crustacean Managed Fishery: SCC) coasts of WA. The west coast component of the stock is certified by the Marine Stewardship Council (MSC) and has been assessed as sustainable. 

There is currently no information on the stock structure of crystal crab. A larval duration of 39 days reported for a congeneric Atlantic Ocean species [Perkins 1973] and preliminary movement information [Melville-Smith et al. 2007] suggest little potential mixing. However, as the majority of the catch (> 95%) comes from a small geographic area, it is considered a single stock for the purpose of this assessment. A research project has commenced to examine the genetic stock structure of crystal crabs from the west and south coasts of Western Australia. Here the assessment is presented at the biological stock level—West Coast (Western Australia).

West Coast

The stock status for Crystal Crab (Chaceon albus) is based on a weight of evidence approach using a range of empirical and modelled estimates of catch, catch rate and biomass in both the West Coast Deep Sea Crab Managed Fishery (WCDSC) and South Coast Crustacean Managed Fishery (SCC). Annual assessments for the WCDSC are have been reviewed by the Marine Stewardship Council (MSC) since 2015.

Catches of Crystal Crab in both of fisheries are limited by individual transferrable quotas.  For the WCDSC, an integrated population model has been developed that estimates percentage depletion from virgin levels for the Crystal Crab across the 10 latitudinal bands that span the active fishery. The combination of latitudinal assessments indicate that the mature biomass is above the provisional target, 60% of virgin biomass (B₆₀) level with a high degree of certainty.  The west coast component of the stock is certified to the Marine Stewardship Council (MSC) and has been assessed as sustainable.  In the SCC Crystal Crab is assessed on a zonal basis, with most of the catch being taken from Zone 2.  This component of the stock is assessed using a biomass dynamics model which indicates that it is likely that the level of stock depletion is adequate, noting that the stock has improved due to sustained low catches of < 5 t over the last four seasons. Projected catches of crystal crab in Zone 2 at current TACs are considered sustainable in the long-term based on current model predictions.

The above evidence also indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired. 

On the basis of the evidence provided above, the West Coast Crystal Crab is classified as a sustainable stock.

[Smith et al. 2004; Melville-Smith et al. 2007] 

Distribution of reported commercial catch of Crystal Crab

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Commercial catch of Crystal Crab

2. Melville-Smith, R., Norton, S.M.G. and Thomson, A.W. (2007). Biological and Fisheries Data for Managing Deep Sea Crabs in Western Australia Final report to Fisheries Research and Development Corporation on Project No. 2001/055. Fisheries Research Report No. 165, Department of Fisheries, Western Australia, 248p.
3. Methot, R.D. and Wetzel, C.R. (2013). Stock Synthesis: A biological and statistical framework for fish stock assessment and fishery management. Fisheries Research, 142: 86-99.
4. Perkins, H.C., 1973. The larval stages of the deep sea red crab, Geryon quinquedens Smith, reared under laboratory conditions (Decapoda: Brachyrhyncha). Fisheries Bulletin, 71:.69-82.
5. Smith, KD, Potter, IC, Hesp, SA (2004). Comparisons between the reproductive biology of females of two species of deep sea crabs that live in different water depths. Journal of Shellfish Research 23:887-896