Reproductive strategy of forkbeard, Phycis phycis, from the Portuguese coast

Abstract

Knowing fish reproductive strategy is essential for understanding population dynamics. This study intends to define the spawning season, length at first maturity, fecundity type, and estimate fecundity of forkbeard, Phycis phycis, from the Portuguese coast. Monthly samples collected from commercial landings between May 2011 and December 2012 were used. Results show that forkbeard is a group-synchronous and batch spawner species. Mature females were found between September and January, mature males were found between August and January, and a significant concomitant increase in gonadosomatic index suggests a spawning season from September to January. Length at first maturity was estimated as 35.9 and 28.5 cm TL for females and males, respectively. Reproductive abnormalitiesmosaic intersex, follicular cysts in ovaries, and early mature males-were detected. For fecundity-type definition, a hiatus between primary and secondary growth oocytes was detected. A significant increase in the mean diameter of secondary growth oocytes and a decreasing trend in their number during the spawning season were observed. The intensity of α-atresia was low throughout the spawning season. These four criteria suggest that forkbeard has determinate fecundity. Mean relative annual fecundity estimated was 1833 ± 857 oocytes g −1 gutted weight. Nonreproductive females that skipped a spawning season attained 36.1 %.

Genetic and Morphological Variation of the Forkbeard, Phycis phycis (Pisces, Phycidae): Evidence of Panmixia and Recent Population Expansion along Its Distribution Area

“…number of nucleotides) [58, 62]. A generation time of one year was assumed, as the forkbeard spawns every year [20], and a mutation rate of 3.86% per million years was considered, based on other gadiform species [67], since no information on mutation rate of the forkbeard is available.…”

“…The forkbeard inhabits on rocky bottoms and sandy-muddy bottoms near rocks at depths up to 650 m [15], taking refuge in holes during the day and becoming an active predator at night [15–17]. In the southern NE Atlantic, the forkbeard is an important commercial species in both Portugal and Spain [18–20], with the landings reaching about 800 tons per year in Portugal [21] and about 4,000 tons per year in Spain [22]. In the Mediterranean, data is only available for Italy, with landings reaching about 300 tons per year [22].…”

“…In the Mediterranean, data is only available for Italy, with landings reaching about 300 tons per year [22]. The forkbeard is one of the most important gadiform species commercially exploited by the Portuguese fleet although its fishery is still classified as developing fishery [18–20]. Despite its economic importance, the population structure of forkbeard is still unknown.…”

Diet and feeding strategy of the forkbeard Phycis phycis (Pisces: Phycidae) from the Portuguese continental coast

“…The forkbeard lives on hard and sandy-muddy bottoms near rocks at depths up to 650 m (Svetovidov, 1986), where it looks for shelter in holes during the day and becomes an active predator during the night, feeding mainly on fish but also on decapods (Papaconstantinou & Caragitsou, 1989; Morato et al ., 1999). In the southern NE Atlantic, forkbeard is an important commercial species, both in Portugal and Spain (Vieira et al ., 2014a, b, 2016a, b), with Portuguese landings reaching about 800 tons per year (INE, 2014). In Portuguese waters, this species is mainly caught by a longline fishery (trawl, trammel net and traps fisheries contribute with a small percentage of the landings) in coastal waters and offshore seamounts, in the mainland area and around Azores and Madeira archipelagos (Vieira et al ., 2014a, b).…”

“…In Portuguese waters, this species is mainly caught by a longline fishery (trawl, trammel net and traps fisheries contribute with a small percentage of the landings) in coastal waters and offshore seamounts, in the mainland area and around Azores and Madeira archipelagos (Vieira et al ., 2014a, b). Despite its economic importance, little information is available on its biology (Silva, 1986; Abecasis et al ., 2009; Matić-Skoko et al ., 2011; Glavić et al ., 2014; Vieira et al ., 2014a, 2016b).…”