Distribution and abundance of snipefish (Macroramphosus spp.) off Portugal (1998-2003)

Abstract

Data from 10 acoustic surveys targeting sardine (spring and autumn), 3 acoustic surveys targeting blue whiting (spring) and 9 groundfish surveys (summer and autumn) were used to describe the distribution and relative abundance of snipefish (Macroramphosus spp.) off Portugal and the Gulf of Cadiz in recent years (1998-2003). Snipefish (8-17 cm) were regularly found off Portugal, occasionally in large concentrations, but were absent from the Gulf of Cadiz. Off northern Portugal, snipefish were distributed along the outer shelf and upper slope, clearly separated from sardine (the most abundant species in the inner shelf) and partially overlapping with blue whiting (Micromesistius poutassou), the most abundant species in the upper slope. Snipefish were most abundant in the outer shelf of south-western Portugal, preferentially distributed in large aggregations around the Canyon of Setubal and partially overlapping with the distribution of boarfish (Capros aper) and blue whiting (both abundant in the upper slope of south-western Portugal). Off southern Portugal snipefish were almost exclusively distributed in the outer shelf and were significantly smaller than in south-western (intermediate) and northern Portugal (large). Acoustic estimates of total snipefish biomass ranged between 176 – 504 thousand tonnes within the study period, with more than half off south-western Portugal. Within the period 1998-2003, and despite the lack of directed fishing activity, a marked decline in abundance and a small but significant increase in mean length were observed, particularly off south-western Portugal.

Keywords

• macroramphosus
• acoustics
• distribution
• abundance
• fish community