First report of an egg-predator nemertean worm in crabs from the south-eastern Pacific coast: Carcinonemertes camanchaco sp. nov

Nemertean worms belonging to the genus Carcinonemertes have been tied to the collapse of crab fisheries in the northeastern Pacific Ocean. A new species is described from egg masses of two commercial crabs, Cancer porteri and Romaleon setosum, inhabiting the central-north Chilean coast. This is the first species of Carcinonemertes described from the southeastern Pacific Ocean. Total body length of Carcinonemertes camanchaco sp. nov. ranged from 2.38 to 4.93 and from 4.29 to 8.92 mm, in males and females, respectively. Among others, traits that distinguish this new species from other previously described congeneric species include: presence of two gonad rows on each side of the intestine, a simple (not decorated) mucus sheath, and a relatively wide stylet basis. Maximum likelihood and Bayesian inference phylogenetic analyses distinguished this new species from all other species of Carcinonemertes with available cox1 sequences in GenBank. Prevalence and mean (± SD) intensity of C. camanchaco sp. nov. was 24% and 2.6 (± 2.07) worms per egg mass in C. porteri and 38.1% and 3.8 (± 2.4) worms per egg mass in R. setosum. The formal description of this new species represents the first step towards the understanding of this worm's impact on the health of crab fisheries in the southeastern Pacific Ocean.

Potential impact of harvesting on Tanner crab (Chionoecetes bairdi) on state of its commercial stock off the coast of Kamchatka

Potential impact of landing on the stock and biological state of Tanner crab is analyzed for two fishery districts at Kamchatka in 2013-2020. In the Kamchatka-Kuril fishery subzone, the number of commercial males without limbs and with old shell increased in catches that may be associated with active operations of alive-crab vessels in 2015-2017. In the Petropavlovsk-Commander fishery subzone, cases of injured Tanner crabs catch became frequent after resumption of the crab harvesting in 2017, as well as the cases of commercial crabs with old shell, that also could be explained by operations of alive-crab vessels. The operations of such vessels are distinguished by strict sorting of caught crabs with removing the individuals of lower quality. As the result, the crabs without limbs and commercial males at late stages before molting were accumulated in the areas of sorting. The problem can be solved by measures for total registration (weighting) of catch before the start of sorting, concerning to all crabs with commercial size landed aboard. To avoid degradation of the Tanner crab population, development of catch processing aboard fishing vessels is recommended, with transportation of frozen products instead of live crabs.