Gender distribution, sexual size dimorphism and morphometric sexing in ballan wrasse Labrus bergylta

Abstract

In wild ballan wrasse Labrus bergylta, mass-length relationships were not different between genders, and positive allometry was found in the mixed-gender population. Male-biased sexual size dimorphism was significant and the most effective morphometric method for sexing L. bergylta outside of the species spawning window used body mass (M(B) in g), total body length (L(T) in mm) and Fulton's condition factor (K) as discriminant variables to predict gender with 91% accuracy. The discriminant score (S(D)) of a specimen can be calculated as S(D) = 0.01 M(B)- 0.016 L(T)- 3.835 K + 6.252 to predict its gender as female or male if S(D) is < 1.459 or S(D) is > 1.504, respectively. There was a potential trend towards earlier sexual inversion compared to previous studies at comparable latitudes. Sex change is a phenotypically plastic trait under social control in haremic fishes and should be monitored in increasingly exploited L. bergylta.

Use of lumpfish for sea‐lice control in salmon farming: challenges and opportunities

“…Better ways of monitoring attrition rates, delousing activity and welfare of lumpfish are also required, as developed for ballan wrasse (Leclercq et al . , ). Survival of lumpfish in salmon cages needs to be better quantified, modelled and monitored under real conditions to achieve the most efficient de‐lousing programmes.…”

Removal of the adhesive gum layer surrounding naturally fertilised ballan wrasse (Labrus bergylta) eggs

“…Prior to the spawning period, fish were separated into 10 spawning tanks holding an average of 17 presumed females and 2 presumed males, as determined by morphometric assessment (Leclercq et al 2014b) [~ 1:10 male: female sex ratio; Mean body-weight (BW) = 1075.5 ± 64.1 g and 765.7 ± 28.9 g for male and female, respectively]. Spawning tanks were housed indoors under SNP each within a 7 m 3 circular tank all connected to a recirculating system using 10% daily exchange of pre-treated pumped ashore natural seawater and a targeted constant 12 °C water temperature.…”

Interbreeding between local and translocated populations of a cleaner fish in an experimental mesocosm predicts risk of disrupted local adaptation

“…Similarly to corkwing wrasse, intraspecific geographic variance in genetic and phenotypic traits has been also reported on goldsinny and ballan wrasse, the other two main cleaner wrasses used by the salmon industry (Halvorsen et al, 2016;Jansson et al, 2017;Leclercq, Grant, Davie, & Migaud, 2014;Sayer, Gibson, et al, 1996). Similarly to corkwing wrasse, intraspecific geographic variance in genetic and phenotypic traits has been also reported on goldsinny and ballan wrasse, the other two main cleaner wrasses used by the salmon industry (Halvorsen et al, 2016;Jansson et al, 2017;Leclercq, Grant, Davie, & Migaud, 2014;Sayer, Gibson, et al, 1996).…”

“…Faust et al (2018) suggested that the proportion of translocated-origin wrasses neighboring a salmon farm in the west coast of Norway may reach almost 40% and our findings provide highly relevant information pertaining to the issue of hybridization and introduction of exogenous genes in such situations. Similarly to corkwing wrasse, intraspecific geographic variance in genetic and phenotypic traits has been also reported on goldsinny and ballan wrasse, the other two main cleaner wrasses used by the salmon industry (Halvorsen et al, 2016;Jansson et al, 2017;Leclercq, Grant, Davie, & Migaud, 2014;Sayer, Gibson, et al, 1996). Hence, considering that millions of cleaner wrasses are annually translocated in Norway (Iversen, 2016) and the UK (Riley et al, 2017) and released inadvertently and intentionally when the net pens are emptied (Blanco Gonzalez & de Boer, 2017), our results should bring awareness of the putative threat pose by wrasse translocations on fitness performance and the long-term evolutionary potential of recipient populations (Araki, Cooper, & Blouin, 2007;Araki et al, 2009;Eldridge & Naish, 2007;Glover et al, 2017;Laikre et al, 2010).…”