Age-based demography of the glacier lanternfish (Benthosema glaciale) in the Flemish Cap

Abstract

It is important to understand the population dynamics of myctophids for a better understanding of the functioning of the ecosystem. In this work, age-based demography parameters of glacier lanternfish (Benthosema glaciale (Reinhardt, 1837)) were calculated. This study was based on 1213 individuals collected in the Flemish Cap during June-July 2008 and 2010. Ages were estimated from counts of annuli in the whole otolith. A strong relationship was found between both diameters of the otolith and fish length, and between otolith weight and increment number. Males predominated in 2008 (37.6% were females) whereas no differences from the expected sex ratio of 1 : 1 were observed in 2010. The somatic growth of B. glaciale is quite fast for the first three years and decreasing thereafter. The von Bertalanffy growth curves revealed interannual differences and no sexual dimorphism in growth. The instantaneous natural mortality coefficient, M, was 0.65 year À1 for the overall population. The maximum age recorded was 7. Our results were compared with age-based demographic parameters from previous studies in the Flemish Cap and in other regions. Because myctophids are considered opportunistic strategists, changes in their demographic features may reflect shifts in the ecosystem.

Age-based life-history parameters of the mesopelagic fish Notoscopelus resplendens (Richardson, 1845) in the Central Eastern Atlantic

“…The size at first maturity was estimated in males at 51.78 mm SL and in females at 55.08 mm SL (Sarmiento-Lezcano, 2016). These values correspond with early values of age at first maturity of 1.7 years for males and 2.05 years for females, similar to those obtained for other myctophids (García-Seoane et al, 2015b).…”

“…and used on many occasions to estimate age and growth in myctophid species (Young et al, 1988;Gartner, 1991a;Linkowski et al, 1993;Greely et al, 1999;Takagi et al, 2006;Bystydzieǹska et al, 2010;García-Seoane et al, 2015a). However, the studies of age and growth using annual deposition patterns and its validation with the microstructure are scarce (Giragosov and Ovcharov, 1992;Greely et al, 1999;Shelekhov, 2004;García-Seoane et al, 2015b).…”

Microstructure of the otoliths of the glacier lanternfish, Benthosema glaciale

“…2c). Previous analysis revealed that the opaque zone combined with a translucent zone was equivalent to one annual increment (García-Seoane et al 2014b). The PMZ showed cyclic patterns of growth similar to the lunar cycles observed by Linkowski (1996) (Fig.…”

“…Otoliths were selected from individuals of Age-classes 1 and 2 (ranging in standard length from 28 to 49 mm), as determined in a study of otolith macrostructure (García-Seoane et al 2014b).…”

Undesirables in Mesopelagic Species and Implications for Food and Feed Safety—Insights from Norwegian Fjords

“…We also observed a trend towards higher concentrations in females of B. glaciale having the same fat content as males, which could be caused by sexual growth dimorphism, with females of certain species investing more energy in reproduction, and thereby growing slower and having more time to accumulate persistent contaminants than males at the same size. However, sexual growth dimorphism was not found in this species in the Northwestern Atlantic [ 78 ] or at the Flemish cape [ 79 ], and neither the mercury concentrations were different between males and females, and further investigations are needed.…”