Deep-sea Red Crab
Download the complete Stock Status Report for Chaceon erytheiae
Stock distribution and identity
One species of deep-sea red crab has been recorded in Division B1, namely Chaceon erytheiae, and is thus considered the target species of this fishery. Aside from the areas recorded in catch records the overall distribution of Chaceon erytheiae within the SEAFO CA is still unknown.
Reported retained catches and discards
Reported landings (Table 1) comprise catches made by Japanese, Namibian, Spanish and Portuguese-flagged vessels to date from 2003-2014. As is evident from Table 2 the two main players in the SEAFO crab fishery are Japan and Namibia, respectively, with Spanish and Portuguese vessels having only sporadically fished for crab in the SEAFO CA over the period 2003 to 2007. Spanish-flagged vessels actively fished for crab in the SEAFO CA during 2003 and 2004, whereas Portuguese-flagged vessels only fished for crab once during the 2007 season (Table 1).
Table 1: Catches (tonnes) of deep-sea red crab (Chaceon spp. – considered to be mostly Chaceon erytheiae).
|Catch details (t)||Ret.||Dis.||Ret.||Dis.||Ret.||Dis.||Ret.||Dis.|
Ret.= retained catch, Dis. = discarded catch. * Provisional (Aug 2014). N/F = No Fishing. Blank fields = No data available. UNK = Unknown.
Being a pot fishery, the deep-sea red crab fishery has an almost negligible bycatch impact. To date only 5kg of teleost (Marine nei and European sprat) fish discards have been recorded, during 2010, from this fishery.
Spatial and temporal distribution of fishing
In the SEAFO Convention Area fishing for deep-sea red crab is focussed mainly on Chaceon erytheiae on Valdivia Bank – a fairly extensive seamount that forms part of the Walvis Ridge (Fig. 1-3). This seamount is located in Division B1 of the SEAFO CA and has been the main fishing area of the crab fishery since 2005 when the resource was accessed by Japan. Records from the SEAFO database indicate that fishing for crab in this area occurred over a depth range of 280-1150m.
Figure 1: The 2014 catch distributions for deep-sea red crab in Division B1 aggregated to a 10 km2 hexagonal area.
Figure 2: The 2013 catch distributions for deep-sea red crab in Division B1 aggregated to a 10 km2 hexagonal area.
Figure 3: The 2012 catch distributions for deep-sea red crab in Division B1 aggregated to a 10 km2 hexagonal area.
Length data and frequency distribution
Available length-frequency data for crabs caught in the SEAFO CA over the period 2010-2014 are presented in Figure 4.
Figure 4: Length frequencies – raised to total catches – of crab caught on Valdivia Bank [2010-2014].
For the period 2010-2014 there have been no significant changes in the female crab size distribution (Fig. 4). The male crab size distribution changed from a wider size distribution in 2010 and 2011, where larger male crabs were recorded, to a slightly narrowed size distribution in 2012-2014 of smaller crabs. Sex ratio from crab commercial samples fluctuated around 4:1 in favour of male crabs – a well-known bias of the commercial traps used in this fishery.