First data on distribution and biology of Squalus blainvillei (Risso, 1826) from the Eastern Mediterranean Sea

Abstract

Longnose spurdog Squalus blainvillei was sampled along the Greek coasts of the northern Ionian Sea during September-October 1999 and April 2000. A commercial motor powered vessel, equipped with a bottom trawl net with stretched mesh size of 20 mm in the codend, was used. The hauls were carried out from dawn to dusk between 300 and 1200 m depths. A total of 733 individuals were collected between 312 and 788 m. Most were distributed in the depth range of 300-500 m in both surveys. The percentage of females in the samples was 47.5% in September-October and 54.5% in April. A wide size-range, up to maximum total length of 785 mm in females and 664 mm in males, was found. The length-weight relationship was calculated for both females and males. Specimens smaller than 300 mm as well as mature individuals of both sexes were found in both September-October 1999 and April 2000. The smallest mature females and males measured 580 and 450 mm, respectively. The size at first maturity was 601 mm in females. At lengths greater than 510 mm all males were mature. The percentages of ripe females were 52.8% in September and 30.3% in April. The sizes of the embryos ranged from 45 to 220 mm total length. The relationship between clasper length and total length was computed.