Occurrence, distribution, and feeding habits of juvenile lumpfish, Cyclopterus lumpus L. in the Bay of Fundy

Abstract

Juvenile lumpfish (< 55 mm length) occur in near-surface waters of the Bay of Fundy from July to September. Samples collected simultaneously with neuston and subsurface nets indicate that the juveniles occur primarily in the top few centimetres of the water column. Seasonal changes in distribution may be related to wind drift of surface waters and the residual circulation of the inner Bay. The length–weight relationship (W = 8.7 L3.36 × 10−6) indicates allometric growth up to 50 mm, at which time lumpfish probably leave surface waters and adopt a pelagic or benthic existence. Juvenile lumpfish feed on a wide range of near-surface plankton, shifting with growth from harpacticoid copepods (particularly Harpacticus chelifer) to the amphipods Calliopius laeviusculus and Parathemisto gaudichaudi.

The effect of temperature and fish size on growth of juvenile lumpfish (Cyclopterus lumpus L.)

“…The first one to two years post hatch juveniles spend summer and autumn in the upper surface waters of tide pools in the intertidal zone (Moring 1990) but some juveniles have also been observed at deep sea (Daborn & Gregory 1983;Davenport 1985). Tide pools offer the young shelter and food in the form of seaweed, other algae and a fluctuating availability of prey between tidal cycles (Moring 1990).…”

“…Small juvenile lumpfish with yolk sacks are found to feed on small crustaceans (harpacticoid copepods) before shifting to amphipods (Callopius laeciusculus and Parathemisto gaudichaudi) with increasing size (Daborn & Gregory 1983;Ingolfsson & Kristjansson 2002). This further indicates an ontogenetic change in terms of prey size in juvenile lumpfish, which further may reflect their change in habitat and hence temperature preference with increasing size (Daborn & Gregory 1983;Brown 1986;Moring 1989). …”

“…Observations by Imsland et al (2000) indicate that juvenile turbot from high latitudes display greater growth capacity and a higher T opt FCE & SGR than that of populations of a southern bound distribution. This rapid growth is assumed to be an effect of short growing season, which may also be an explanatory factor for the small size of lumpfish in the Bay of Fundy (Daborn & Gregory 1983;Davenport 1985) relative to other observations of counter specimens further north, though temperatures in shallow areas of the Bay of Fundy are observed to reach 0 -4 °C in winter (Campbell & Stasko 1986). It is also possible that the individual differences in growth were due to sex-related differences, as lumpfish females generally are larger than male specimens of the same age (Davenport 1985;Moring 2001).…”

“…Spawning often takes place in shallow sub tidal waters when temperatures reach around 4 °C (Collins 1976;Daborn & Gregory 1983) and females spawn 1-3 batches of adhesive eggs (Andrijasev 1964;Collins 1976;Daborn & Gregory 1983). Males enter fjords prior to females to establish nesting sites, usually depressions in the substrate in the near-shore tidal zone (Goulet et al 1986).…”

“…Males enter fjords prior to females to establish nesting sites, usually depressions in the substrate in the near-shore tidal zone (Goulet et al 1986). Each female produces approximately 80 000 -159 000 eggs per spawning season (Andrijasev 1964;Collins 1976;Daborn & Gregory 1983). The sex-ratio of lumpfish catches is imbalanced, Bañón et al (2008) found a 7 : 1 proportional balance favorable to female lumpfish, which is probably favorable to the spawning season as males are observed to take care of several batches at once (Mitamura et al 2012).…”