Bioecological lessons learned from the neonate longnose spurdogs Squalus blainville (Squaliformes: Squalidae) suggest a potential nursery ground in the Marmara Sea

Abstract

The capture of 176 neonate longnose spurdogs Squalus blainville (Risso, 1827), suggests a potential nursery ground in the eastern Marmara Sea (GFCM GSA28). Sampling was performed by means of a scientific bottom trawl hauled at a depth range of 121-126 m on 21 February 2024. Available data show that S. blainville may be captured in demersal fishery within their first year of life. Total length (TL) and total weight (TW) of the examined males ranged from 169 to 279 mm (238.4±20.7 mm) and from 21.4 to 117 g (66.5±19.8 g), respectively. The TL and TW of the examined females ranged from 187 to 292 mm (241.1±25.3 mm) and from 30.1 to 146 g (66.8±29.2 g), respectively. A male neonate (TL=169 mm) examined is believed to be the smallest free-swimming longnose spurdog caught to date. Under current fisheries regulations, S. blainville is a protected shark species in the waters of Türkiye and therefore should be released if caught as bycatch. However, in addition to reducing fishing pressure on the species by prohibiting targeted fishing, area-based conservation actions, which are based on closing areas that are critical for chondrichthyans (e.g., nurseries) to fishing either on a year-round or seasonal basis, should now be included in the conservation plans for S. blainville and other protected species in Turkish waters.