How the Humboldt squid’s genetic past and present can secure its future — ScienceDaily
A group of marine biologists is pushing for more international collaboration to manage the Humboldt squid population after their study to identify its genetic stocks revealed its vulnerability to overfishing by fleets trying to feed the world’s hunger for squids.
Hiroshima University marine biologist Gustavo Sanchez led a team of researchers to find out the genetic structure of the Humboldt squid population in the Eastern Pacific Ocean using two types of DNA markers — the mitochondrial ND2 gene and nuclear microsatellite loci.
The team found that Humboldt squids could trace back their population to three historical matrilineage that spread out during the late Pleistocene and that the species has at least two contemporary genetic stocks homogeneously co-distributed in the northern and southern hemispheres.
Different genetic stocks within a species are usually defined by where they feed and breed. But in Humboldt squids, DNA markers showed no north-south divide. The equator doesn’t serve as a natural barrier to separate the different genetic stocks of these fast swimmers risking capture by different fishery fleets along their migration route.
“In our study, we identify at least two genetic stocks co-distributed in the north and southern hemisphere of the Eastern Pacific Ocean. Our results suggest that rather than independent marine policies from each country, the sustainability of this squid requires an international marine policy,” Sanchez said.
To ensure sustainable fishing, countries in South America where the squid is traditionally found have established yearly catch quotas. But the study found this approach to be ineffective, especially as catch restrictions are absent in international waters on the squid’s migration path.
“Countries fishing this squid have established catch quotas with no consideration that the total amount varies from year to year, and that the amount of squid caught influences the number of squids next year. By doing