Aerial and Acoustic Surveys for Mackerel - BioSonics, Inc

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In June, mackerel stock distribution was governed by hydrological conditions in the region (Figure 5.1.2.2). Small schools were found at depths 10 to 25 m in Eastern and South-Eastern part of the research area. Temperature of the water in above areas was higher than 9°C. In the Western part of the research area, where isothermal line of 9°C was very close to the surface, echograms from echo-sounder, showed no or very small number of mackerel schools. Measured Nautical Area Scattering Coefficients (S A ) for 5 mile intervals varied from 1 to 30 (m 2 /nmi 2 ). Maximal mackerel schools were registered in position 65°45’N, 4°W. Low NASCs resulted from the fact that most of the fish avoided the vessel. Therefore, acoustic estimation of mackerel was not calculated. The trawl method was used for estimating the biomass and distribution of mackerel schools. During the survey, the vessel made a total of 31 trawl hauls. Mean length of fish and mean weight of mackerel were 36.06 cm, 526 g accordingly. A preliminary result gave a biomass estimate of 720 000 tones. During the survey, the RV “Smolensk” worked in conjunction with the research aircraft under the joint program (see above). 69° 108 109 110 148 149 150 151 68° 113 155 112 154 153 111 152 114 115 116117 156 157 158 159 160 161 162 163 164 165 166 67° 173 172 121 171 170 120 169 119 168 118 167 122 123 124 125 174 175 176 177 178 129 128 127 126 66° 184 183 182 181 180 179 130 131 132 133 185 186 187 188 189 190 191 192 193 135 134 197 136 196 195 194 65° 137 138 198 199 - CTD - Ï åë. òðàë 64° -8° -6° -4° -2° 0° 2° 4° Figure 5.1.2.1. Survey tracks, trawl and hydrographic stations RV “Smolensk”. PGAAM Report 2004 11
69° 68° 67° 200 66° 100 25 5 65° 1 0 64° -8° -6° -4° -2° 0° 2° 4° Figure 5.1.2.2. Distribution of mackerel as a result of a trawl survey by RV “Smolensk” (t/n.mi 2 ). 5.1.3 Norwegian trawl survey During 15–30 July two Norwegian commercial purse seiners, “Endre Dyrøy” and “Kings Bay” carried out a trawl survey at prefixed stations. “Endre Dyrøy” started in the south and worked northwards while “Kings Bay” started in the north and worked southwards. Both vessels trawled the surface layer (the upper 40 m) at each station for 30 minutes. The distributions of catches are given in Figure 5.1.3.1. The largest catches were taken in the southern area, while the catch rates in the international zone were relatively low. The largest mackerel were caught in the Jan Mayen area. 12 PGAAM Report 2004
Page 1 and 2: Living Resources Committee ICES CM
Page 3 and 4: TABLE OF CONTENTS Section Page 1 IN
Page 5 and 6: The main objectives of PGAAM are to
Page 7 and 8: (f) σ/σ ref Level could change
Page 9 and 10: empirical requirements must be fulf
Page 11 and 12: Figure 5.1.1.1. Flights tracks of R
Page 13: The results of airborne research ha
Page 17 and 18: Figure 5.2.1.a. The planned survey
Page 19 and 20: 6.1.2 Scottish survey The survey Th
Page 21 and 22: ased on the findings of the SIMFAMI
Page 23 and 24: NASC (m2.nm-2) 1600 1400 1200 1000
Page 25 and 26: 62° 61° 60° 59° -2° -1° 0° 1
Page 27 and 28: Figure 8.3. Catch rates of mackerel
Page 29 and 30: Resource Requirements Participants
Page 31: ANNEX 1: LIST OF PARTICIPANTS PLANN

Aerial and Acoustic Surveys for Mackerel - BioSonics, Inc

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