New clues on the Atlantic eels spawning behavior and area: the Mid-Atlantic Ridge hypothesis

Abstract

The Sargasso Sea has long been considered as the only spawning area for Atlantic eels, despite the absence of direct observations. The present study raises a novel scenario, deviating from Schmidt’s dogma, begins with a review of historical and recent observations that were combined to build up a global theory on spawning ecology and migration behavior of Atlantic eels. From this, it is argued that a favorable spawning area could be located eastward of Sargasso Sea at the intersection between the Mid-Atlantic Ridge and the oceanic fronts. Ocean circulation models combined with 3D particle-tracking method confirmed that spawning at this specific area would result in larval distribution fitting the field observation. This study explores the hypothesis that leptocephali are able to swim and orientate to reach their specific growth areas. It proposes a novel framework about spawning ecology, based on orientation, navigation and meeting cues of silver eels to the spawning area. Together this framework may serve as a stepping-stone for solving the long-lasting mystery of eel reproduction which first came out 2,400 years ago and promotes the understanding of oceanic migration and reproduction of marine organisms.

Important questions to progress science and sustainable management of anguillid eels

“…One important feature of the spawning migrations of anguillid eels reported in these studies is the repeated, but so far only partly explained occurrence of significant daily vertical migrations (DVM). Eels reside in very deep water during the day (between about 600 and 900 m) and move into shallower water during night‐time (between about 100 and 300 m) (Chang et al, 2020; Manabe et al, 2011; Righton et al, 2016; Schabetsberger et al, 2016), sometimes over temperature ranges of up to 20°C. The occupation of deep water during the day is generally accepted to be an anti‐predator behaviour with a strong link to illumination (Jellyman & Tsukamoto, 2010; Righton et al, 2016; Schabetsberger et al, 2016; Wu et al, 2018).…”

“…Further integration of biological and oceanographic disciplines will continue to enhance knowledge in this area of work (e.g. Chang et al, 2020).…”

Assessing Temporal Patterns and Species Composition of Glass Eel (Anguilla spp.) Cohorts in Sumatra and Java Using DNA Barcodes

“…Likewise, mechanisms inducing glass eel migration choices may account for these large differences between glass and yellow/silver eel mitochondrial genetic diversity. Natal homing, that is migration directed towards parental habitats, is currently observed for A. anguilla and A. americana, which seemingly share spawning grounds in the Atlantic Ocean and hybridize but whose yellow/silver eels do not co-occur in Europe and North America [89][90][91]. Alternatively, inter-annual variability in reproductive success and larval survival might be responsible for these large differences between glass and yellow/silver eel genetic diversity in A. marmorata, A. bicolor and A. bengalensis/A.…”

Abundance and Distribution of American Eel in a Heavily Dammed Urban River

“…American Eels spawn from the Sargasso Sea to the Mid‐Atlantic Ridge (Chang et al. 2020), with larvae being passively transported from there by the Gulf Stream before dispersing to watersheds from northeastern South America to Labrador and Greenland (Vélez‐Espino and Koops 2010). The larvae morph into transparent glass eels as they approach estuaries and rivers but then quickly transform to pigmented “elvers.” American Eels appear to undergo environmental sex determination, with males dominating in more saline waters where population densities are higher and females in fresher environments where population densities are lower (Krueger and Oliveira 1999).…”