Molecular Identification of Hammerhead Shark Trunks from the Southern Gulf of California using Multiplex PCR

The demand for shark fins in Asiatic markets has resulted in excessive increases in shark catches,even for species that may be under protection or subject to management.As such,it has been necessary to develop and promote monitoring efforts for exploited species and taxonomic groups in order to improve fishing management strategies for elasmobranchs.Identifying species from landings is one of many fishing management problems because landed organisms have usually already been processed and are therefore incomplete,which makes identification problematic,impedes the generation of proper species records,and leads to poor fishery assessments.Tools that can correctly identify species,such as various molecular techniques,have become essential for accurate fishery assessments.In this study,30 hammerhead trunks from artisanal fisheries from the southern portion of the Gulf of California were identified using multiplex PCR(17 Sphyrna lewini and 13 Sphyrna zygaena).The total fee to identify each trunk with this technique was~$3.80 and the procedure required 2 to 5 days.When compared with other widely-used methods,such as PCR-RFLP or barcoding,multiplex PCR is fast,efficient,low-cost,and easy to implement in a laboratory.

Unraveling the morphological patterns of a subantarctic eelpout:a geometric morphometric approach

Phenotypic variation in organisms depends on the genotype and the environmental constraints of the habitat that they exploit.Therefore,for marine species inhabiting contrasting aquatic conditions,it is expected tofind covari-ation between the shape and its spatial distribution.We studied the morphology of the head and cephalic sensory canals of the eelpout Austrolycus depressiceps(4.5–22.5 cm TL)across its latitudinal distribution in South Pacific(45°S–55°S).Geometric morphometric analyses show that the shape varied from individuals with larger snout and an extended suborbital canal to individuals with shorter snouts and frontally compressed suborbital canal.There was size variation across the sampled populations,but that size does not have a clear latitudinal gradient.Only 8%of the shape variation relates to this size variation(allometry),represented by a decrease in the relative size of the eye,and a depression of the posterior margin of the head.There were spatial differences in the shape of the head,but these differences were probably caused by allometric effects.Additionally,2 of the canals of the cephalic lateralis pores and the head shape showed modularity in its development.This study shows that the morphology of marinefish with a shallow distribution varies across distances of hundreds of kilometers(i.e.,phenotypic modulation).