Impact of hatch date on early life growth and survival of Mueller’s pearlside (Maurolicus muelleri) larvae and life-history consequences

Abstract

Growth and survival of Maurolicus muelleri larvae in Herdlefjorden, Norway, were investigated by daily otolith increment analysis. While high egg densities were generally observed throughout the spawning season, three cohorts each with a narrow window of hatching dates were identified. The first of these cohorts was characterized by low growth and poor morphometric condition and disappeared from the fjord during autumn. High-resolution drift modeling indicated that Herdlefjorden had a net export of larvae and negligible import in the period cohort 1 disappeared. Yet, the advective loss rate of larvae was not considered high enough to explain the near complete disappearance of the first cohort. An otolith-based growth chronology indicated that growth conditions in Herdlefjorden improved noticeably around mid-September and remained favorable the following month. The analysis of daily otolith increments could thus be used to document within-season variability in larval growth and survival. The low and variable survival due to short-term fluctuations in environmental conditions indicate that multiple batch spawning is an adequately evolved life-history strategy for marine planktivorous fish such as M. muelleri.Résumé : La croissance et la survie des larves de Maurolicus muelleri dans le Herdlefjorden (Norvège) ont été étudiées par l'analyse des incréments quotidiens d'otolithes. Si de fortes densités d'oeufs ont été généralement observées durant toute la saison de frai, trois cohortes ont néanmoins été identifiées, chacune présentant sa propre fourchette restreinte de dates d'éclosion. La première cohorte était caractérisée par une faible croissance et un faible embonpoint morphométrique et a disparue du fjord durant l'automne. La modélisation à haute résolution de la dérive indique que le Herdlefjorden présentait une exportation nette de larves et une importation négligeable dans la période durant laquelle la première cohorte a disparu. Le taux de perte de larves par advection n'est toutefois pas jugé assez élevé pour expliquer la disparition presque complète de la première cohorte. Une chronologie de la croissance reposant sur les otolithes indique que les conditions de croissance dans le Herdlefjorden se sont améliorées de manière marquée vers la mi-septembre et sont demeurées favorables le mois suivant. L'analyse des incréments quotidiens d'otolithes pourrait donc être utilisée pour documenter la variabilité au cours d'une même saison de la croissance et de la survie des larves. Une survie faible et variable causée par des fluctuations de courte durée des conditions ambiantes indique que frayer en plusieurs épisodes constitue une bonne stratégie d'évolution du cycle biologique pour les poissons marins planctonivores comme M. muelleri. [Traduit par la Rédaction]

Exploring Growth Patterns of Maurolicus muelleri across Three Northeast Atlantic Regions

“…The estimated mean somatic growth rate for M. muelleri in the BoB (0.20 mm day⁻ 1 ) is comparable to that reported by [36], who studied the growth of M. muelleri larvae in a Norwegian fjord (0.20 mm day⁻ 1 ), and slightly lower than the estimate for juveniles in the CS area (0.26 mm day⁻ 1 ) [21]. Slower growth rates were also observed in other congeners: M. stehmanni in Brazilian waters (0.19 mm day⁻ 1 ) [37], M. australis larvae (0.16 mm day⁻ 1 ) in Chilean Patagonia [38], and M. mucronatus (0.15 mm day⁻ 1 ) in the Red Sea [39].…”

The revolution of crossdating in marine palaeoecology and palaeoclimatology

“…For some species such as tropical corals, the expense of sampling can be high, but where replication is available, crossdating can yield annually resolved, environmentally sensitive chronologies [20,25,54 -56]. Crossdating may also be possible with increments (or layers) in coralline algae, deep sea corals, sclerosponges, speleothems, ice cores, varved sediment cores and perhaps in sub-annual (daily or tidal) increments [57][58][59]. If increment widths are not visually evident or lack adequate interannual variability, crossdating could be attempted using chemical or morphological properties such as trace and minor element concentrations, isotope signatures, shell microstructures, or even the brightness of the internal banding structure [39,43,55].…”

Early development of pearlside Maurolicus stehmanni off south‐eastern Brazil

“…We hypothesized that the morphometric variations observed between M. stehmanni and other Maurolicus species, mainly in the ray count of the anal fin and the photophore development sequence, may be due to phenotypic plasticity/variability or genetic differences. Nutritional status can also account for photophore number variation (Folkvord et al ., 2016).…”