Investigating species identity and distribution of commercially important squids

Squids, particularly the scientific genus Illex, are of great importance to global fishing industries and include four species: I. coindetii, I. illecebrosus, I. argentinus and I. oxygonus. These species are difficult to distinguish in the field, leading to potential mislabeling issues. Limited knowledge of Illex spp. biology and their migrations due to climate change can further complicate the identification. In the Italian market, I. coindetii has a higher economic value compared to the other species, as it is caught in the Mediterranean Sea by local fishing companies, and consumers are willing to pay more for local products. Due to the identification challenges, the squid's commercial name on the label is correlated to the fishing area, especially for I. coindetii and I. illecebrosus, which have similar morphology. Nowadays, in the fishery platform, no further analysis can confirm the commercial attribution, but different recent research suggests there could be an overlapping distribution of these two species. To better understand Illex species distributions, 31 specimens were selected from 26 different lots and caught in three different fishing areas of the Atlantic Ocean and Mediterranean Sea (FAO areas 27, 37, and 41), to include the highest variability possible. The species studied are I. coindetii, I. illecebrosus, and I. argentinus; the former two are the most difficult to differentiate, while I. argentinus is more clearly defined both geographically and morphologically, allowing easier identification. For each specimen, morphometric analysis were performed by collecting eight measures of soft body structures, and six measures each for the upper and lower chitinous beaks, with DNA barcoding of the mitochondrial cytochrome C oxidase subunit I gene, to identify the corresponding species. Combined DNA barcoding and morphological measures proves to be a methodology able to distinguish the squid species and to better define the population of fishing stocks. This approach could be useful to delineate species distribution area and assess potential overlaps, supporting the fishery management and the development of faster identification methods. Furthermore, if all the squid specimens from areas 27 and 37 are confirmed to be I. coindetii, this may indicate that the population area is wider than expected, and changes in the labelling legislation may be needed to avoid commercial fraud.

Squids, particularly the scientific genus lllex, are of great importance to global fishing industries and include four species: I. coindetii, I. illecebrosus, I. argentinus and I. oxygonus. These species are difficult to distinguish in the field, leading to potential mislabeling issues. Limited knowledge of Illex spp. biology and their migrations due to climate change can further complicate the identification. In the Italian market, I. coindetii has a higher economic value compared to the other species, as it is caught in the Mediterranean Sea by local fishing companies, and consumers are willing to pay more for local products. Due to the identification challenges, the squid's commercial name on the label is correlated to the fishing area, especially for I. coindetii and I. illecebrosus, which have similar morphology. Nowadays, in the fishery platform, no further analysis can confirm the commercial attribution, but different recent research suggests there could be an overlapping distribution of these two species. To better understand Illex species distributions, 31 specimens were selected from 26 different lots and caught in three different fishing areas of the Atlantic Ocean and Mediterranean Sea (FAO areas 27, 37, and 41), to include the highest variability possible. The species studied are I. coindetii, I. illecebrosus, and I. argentinus; the former two are the most difficult to differentiate, while I. argentinus is more clearly defined both geographically and morphologically, allowing easier identification. For each specimen, morphometric analysis were performed by collecting eight measures of soft body structures, and six measures each for the upper and lower chitinous beaks, with DNA barcoding of the mitochondrial cytochrome C oxidase subunit I gene, to identify the corresponding species. Combined DNA barcoding and morphological measures proves to be a methodology able to distinguish the squid species and to better define the population of fishing stocks. This approach could be useful to delineate species distribution area and assess potential overlaps, supporting the fishery management and the development of faster identification methods. Furthermore, if all the squid specimens from areas 27 and 37 are confirmed to be I. coindetii, this may indicate that the population area is wider than expected, and changes in the labelling legislation may be needed to avoid commercial fraud.