Codend selectivity for jack mackerel and whitefin jack and unequal split parameter estimates observed in trouser trawl experiments

Abstract

Codend selectivity for the jack mackerel Trachurus japonicus and the whitefin jack Kaiwarinus equula were evaluated based on data from trouser trawl experiments carried out in the East China Sea, using a test codend of 60 mm diamond mesh and a control codend made of minnow net with a square mesh of 9 mm bar length. Between-haul variations in parameters and the mean selection curves were tested with the catch data in the SELECT approach, and then the model of between-haul variation in the split parameter with the mean selection curve was chosen as the best fit using Akaike's information criterion model selection. The 50% retention lengths and the selection ranges were 11.4 and 3.36 cm for jack mackerel and 8.83 and 0.93 cm for whitefin jack, respectively. The selection curve for whitefin jack was sharp, whereas that for jack mackerel was relatively wide. As the estimated split parameters indicated, about 80% of the whitefin jack entered the control codend, but 85 and 90% of the jack mackerel entered the control codend in the second and third hauls, respectively. The inequality in the split parameter is discussed from the viewpoint of the animal's swimming behavior and water movement based on underwater video observations.

Complete Mitochondrial Genome of Pseudocaranx dentex (Carangidae, Perciformes) Provides Insight into Phylogenetic and Evolutionary Relationship among Carangidae Family

“…The generation of the P. dentex mitogenome in the present study was helpful to clarify the nomenclature and taxonomy of C. equula. By applying the whole mitochondrial genome, COI, and CYTB genes of available Carangidae fishes, our results confirmed C. equula should belong to the Kaiwarinus genus, in line with results from other scholars [9,12,45,46]. Combining the results discussed above, we inferred that Kaiwarinus equula should be the accepted name instead of Carangoides equula and belong to an independent genus which is the sister genus of Pseudocaranx.…”