Sevigny et a\: Identification and distribution of larvae or Sebastes fasciatus and 5, mentella 



381 



52° 



Belle Isle Strati 



Quebec 



57° 



Figure 3 



Geographic distribution of the larval genotypes MDH*A1A1 characteristic of S. men- 

 tella (white), MDH*A2A2 caracteristic of S. fasciatus (black) and MDH*A1A2 (gray) in 

 June-Julv 1991. 



Results 



Larval distribution, abundance, and size 



In 1991, redfish larvae were caught at all but three 

 sampling stations that were shallower than 200 m 

 (Fig. 1). Lai-val abundance was highest (max. =62. 6 

 individuals/m'-) over the central portion of the Lau- 

 rentian Channel, on the southeastern side of Anti- 

 costi Island, and decreased northward along the 

 Esquimau Channel. Only one larva was captured at 

 the northeasternmost sampling station (12) (Fig. 1; 

 Table 1). On the western side of Anticosti Island, 

 larval abundance was highest (max.=13.8/m-) at the 

 central stations of the transect. Few larvae were 

 caught at coastal stations within the Gaspe current 

 (stations 26-28) or at the northernmost sampling 

 station (<200 m deep) (Fig. 1; Table 1). 



In 1992, larvae were collected at 34 of the 74 sam- 

 pling stations (Fig. 2), and centers of abundance 

 (max =125.4 larvae/m-) were again located in the 

 Laurentian Channel. Abundance gradually declined 

 northwards along the Esquimau Channel. Larval 

 redfish were virtually absent at the mouth of the 



Belle Isle Strait, along the Quebec north shore, at 

 the shallow (<200 m) sampling stations on the north 

 side of Anticosti Island or at the tip of the Gaspe 

 peninsula (Fig. 2; Table 2). 



The size of larvae ranged from 5.0 mm to 12.3 

 mm in 1991 and from 5.6 mm to 10.9 mm in 1992 

 (Tables 1 and 2). Larvae collected in 1991 were signi- 

 ficantly larger than those collected in 1992 (Mann- 

 Whitney U-test, P<0.0001; Table 1). Larvae from the 

 eastern sector in 1991 were larger than those col- 

 lected in the western sector (Mann-Whitney U-test, 

 P<0.0001), and larvae collected in the eastern sector 

 in 1991 were significantly larger than those collected 

 in approximately the same region in 1992 (Mann- 

 Whitney [/-test, P<0.0001). 



Spatial and temporal genotypic variations 



The three genotypes were found in larval redfish and 

 their relative proportion varied between sites and 

 years (Figs. 3 and 4; Tables 1 and 2). In 1991, two 

 groups of stations could be identified on the western 

 side of Anticosti Island (stations 26-34) based on 

 the frequencies of the genotypes observed. The first 



