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4 DISCUSSION

Another sternoptychid species, Maurolicus muelleri, is known to spawn over the shelf and slope, however the only specimen in our study was found far north from Gran Canaria where the bottom depth is more than 1300 m. This may indicate a drift by a northern filament from the West African coast into the open ocean. The seasonal occurrence of M. muelleri was incongruent with previous studies (JOHN et al. 2004a). These authors observed the highest catches during winter season, while no larva could be found during winter cruises in the present study, but only during May. The occurrence of Vinciguerria larvae is concentrated from the surface water down to 50 m, but when they start to transform they migrate vertically down to 300 – 400 m (BADCOCK 1994). In the present study most larvae were found in the upper meters, but since larvae were in post flexion stage and some already in the transformation stage, several specimens were found deeper, even down to 500 m already in the process of migrating down to their adult habitat. RODRÍGUEZ et al. (1999) found V. poweriae to be the most common species among the genus Vinciguerria during August 1993, while during our investigations V. attenuata was the most abundant species with a peak in May. V. attenuata was mainly found at oceanic stations far north of the islands, while V. nimbaria seem to be more associated to the islands and was intermediate in its occurrence with the highest abundance in autumn. V. poweriae was rare throughout the period of investigation. In JOHN et al. (2004a) V. nimbaria was most abundant throughout all seasons, except for autumn, which was not included in their investigations. This species had its peak during March. Intermediate in its occurrence was V. attenuata, but not found in winter and V. poweriae was lowest in abundance and not found in March. The overall tendency that can be seen is that V. poweriae is most abundant in summer (JOHN et al. 2004a; RODRÍGUEZ et al. 1999), which is congruent with BADCOCK (1984). In our study V. nimbaria has its peak in autumn, but no further information about this season can be found in other studies. In the study of JOHN et al. (2004a) V. nimbaria was most common in March. V. attenuata is most common in May according to the present study, and in summer according to the data from JOHN et al. (2004a).

4.2.2. Comparison with adult fish WIENERROITHER (2003 and 2005) investigated adult fish material caught in the same surveys the larval material of this study derives from. Concerning the adult fish fauna WIENERROITHER (2003) observed mesopelagic species from the cruise La Bocaina 11/97 and ECOS 04/99, where the families Myctophidae, Gonostomatidae, Phosichthyidae and Stomiidae made up about 95 % of the total catch around the Canary Islands, although trawls in neritic, epipelagic and mesopelagic realm were taken. Concerning only mesopelagic fish larvae, Gonostomatidae were the most abundant next to Myctophidae, Phosichthyidae and Paralepididae. The most diverse family within the larval community are the Myctophidae, which is similar to the findings of WIENERROITHER (2003 and 2005). Within the adult Myctophidae Hygophum hygomii was the most abundant species in all seasons (WIENERROITHER 2005), while only a few larval specimens were caught. Ceratoscopelus warmingii and Lobianchia dofleini (ZUGMAYER, 1911) were very abundant in the adult fish material (WIENERROITHER 2005). In the larval material some specimens of larval C. warmingii occurred, but no larval L. dofleini. Within the adult Gonostomatidae Cyclothone sp. was the most dominant genus (WIENERROITHER 2005), while only a few Cyclothone larvae were found in identical trawls. This result may at least in part reflect a general underprepresentation of small larvae due to the methodology as discussed before. Adult Gonostoma elongatum GÜNTHER, 1878 was more abundant than G. denudatum (WIENERROITHER 2005), while G. denudatum was abundant in larval material, no larval G. elongatum was found at all. Congruent with WIENERROITHER (2005), the paralepidid Lestidiops sp. was most abundant in autumn season in larval and adult study. Further, none of the demersal indicator species found by LORANCE et al. (2001) was represented in the larval material. Overall, the larval community sampled seems not to reflect the species composition of the adult fish assemblage. Only a small portion of the adult fish

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Inf. Téc. Inst. Canario Cienc. Mar. n°13

Spatial and seasonal patterns in species composition of fish larvae in the Canary Islands  

Technical report consisting on a comprehensive annotated larvae taxa list with the most important taxonomic characters of this region

Spatial and seasonal patterns in species composition of fish larvae in the Canary Islands  

Technical report consisting on a comprehensive annotated larvae taxa list with the most important taxonomic characters of this region

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