R1/12
Not to be cited without prior reference to the FRS Marine Laboratory, Aberdeen Scotia
Cruise 0507S Report
3 -23 April 2007 Ports
Loading: Aberdeen, 2 April Half Landing: Killybegs, 10 April Unloading: Aberdeen, 23 April
Personnel
F Burns (In Charge) E Armstrong
M Campbell R Watret A Tait
I Gibb (10 – 23 April)
Out –turn Days per Project: 20 days to MF01TA Objectives
1. To carry out mackerel egg survey (ICES Triennial Survey), on the western shelf and shelf edge in the area from50oN to 60o N using the Gulf VII plankton sampler.
2. To collect adult samples of mackerel and horse mackerel, by trawling, for atresia and fecundity analysis.
Narrative
Scotia sailed from Aberdeen at 1200 on the 3 April and proceeded to an area east of Peterhead to perform calibrations on the sampler flowmeters. Scotia then proceeded northwards and arrived at the first station (59°45N, 5°15W) at approximately 1000 on the 4 April to commence the survey. Survey stations at 30’E/W intervals, on transects separated by one degree of latitude, were conducted successfully during the outbound survey run until on the 10 April the Scotia arrived in Killybegs for the midcruise break at which point Iain Gibb joined the vessel. On the afternoon of the 11 April Scotia resumed the survey continuing south using the same transect spacing and sampling intervals as before until reaching the southern survey boundary at 50°45N. Because of the large size of the survey area comprehensive coverage of the return leg of the survey was not going to be possible.
Consequently Scotia interlaced back north on the return leg using alternate transects to those covered on the first outbound leg targeting areas of high abundance as well as firming up boundary coverage missed during the outbound leg of the survey. The survey was completed east of Cape Wrath by 1000 on Sunday 22 April and Scotia made for Aberdeen, docking in the early hours of Monday 23 April.
1
2 Results
A total of 152 plankton stations (see Figure. 1) and 21 calibration stations were collected during the cruise with the Gulf VII. All samples were sorted for fish eggs during the survey with the eggs also being successfully staged and identified at sea for mackerel and horse mackerel. The highest density of mackerel eggs were recorded at a location on the shelf edge northwest of Donegal. In addition large numbers of mackerel eggs were encountered on the shelf edge west of Ireland and at locations east of the porcupine bank. Overall, the mackerel egg concentrations were located along the 200m contour with eggs being encountered in varying numbers along the entire length of the survey area at this depth.
Numbers of horse mackerel eggs were low throughout the survey area with only one sample location yielding significant numbers. Generally horse mackerel displayed a much more southerly distribution compared with mackerel. The only large concentration of horse mackerel eggs on this survey is located right on the southern boundary of the survey area on the shelf break at 50°45N. The distribution of mackerel and horse mackerel eggs at stage 1 and for all stages are shown in figures 2 to 5. The majority of stage 1 mackerel eggs appear to follow the general pattern described above with very few being encountered north of 56°N. This is in contrast to the results seen 3 years ago during this period where much greater concentrations of stage 1 mackerel eggs were encountered above 57°N although the full conclusions must wait for the assimilation of the full survey database. Egg production results from this survey will be included in the international database for further analysis.
In addition to the mackerel egg samples, plankton samples were also collected for Steve Hay for genetic sub population plankton analysis. These were collected from a pup net which was attached to the side of the Gulf VII sampler. These samples were then placed in ethanol for analysis back in the lab.
A total of five tows were carried out using the GOV trawl to collect mackerel and horse mackerel ovaries for fecundity and atresia assessment. Information on length, total weight, liver weight and age was also collected from each sample. Due to the success of the GOV in catching the target species the PT160 was not used during the survey.
Sea surface temperature and salinity were collected continuously using the thermosalinograph whilst cast profile information on temperature and salinity were recorded at each Gulf VII station using a Seabird 19 CTD.
Finlay Burns 25 May 2007
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307
306 305 304
302 303 300 301 299 297 298 296 295
294 293 292 291 290 289 288 287
286 285 284 283 282 281
280 279 278 277 276 275 274 273 268 267 266 265 264 263 261 262 259 260 257 258 256 255 254
253 252 251 250 249 248 247 246 245 244
243 242 241 240 239 238 237 236 235 234 233 232 231
230 229 228 227 226 225 224 223 222 221 220 219 218 217 216
215 214 213 212 211 210
209 208 207 206 205
204 203 202 201 200 199
198 197 196 195 194 193 192 191 190 189 188 187 186 185 184 183 182 181 180 179 178
177 176 175 166 165 164 163 162 161
158 157 156 155 154 153 152 151
150
149 148 147 146 145 144 143
4°W 4°W
5°W 5°W
6°W 6°W
7°W 7°W
8°W 8°W
9°W 9°W
10°W 10°W
11°W 11°W
12°W 12°W
13°W 13°W
14°W 14°W
15°W 15°W
16°W 16°W
60°N 60°N
59°N 59°N
58°N 58°N
57°N 57°N
56°N 56°N
55°N 55°N
54°N 54°N
53°N 53°N
52°N 52°N
51°N 51°N
0407S - Gulf VII Sample Positions
! Sample position and number 500m
200m
Figure 1: 0407SGulf sampler positions. Locations of fish trawls using the GOV are denoted by blue circle on map).
Figure 2: 0407S – Total numbers of mackerel eggs recorded.
2 4
6
4 4 3 6
9 0 2 3
4 0 0 1
0 0 3
0 1 1 1 0 2
0 0 0 1 2
2 1
1 2
4 0 7 2
6 3 0 7
0 2 4 1
1
7 9 8 1
0 3 1 7 7 0 0 0 0 0
0 1 1 1
5 0
6 0
0
0 0 0 0 0 0
35
24 71 67 18
70 44 35 31
11 34
16 31 25 60 10
23 89
23 35 98 24
14 82 13
28 75
25 19 40 34
22 27 46
13 45 15
12
38 11 17 13
22 47 29 23 14
14
156
236
202 235 180 242
120 458
134 209 187 416 237 310 197 114
281 402 487 128 389 279 116 188
647 425 137 808 116
5°W 5°W
6°W 6°W
7°W 7°W
8°W 8°W
9°W 9°W
10°W 10°W
11°W 11°W
12°W 12°W
13°W 13°W
14°W 14°W
15°W 15°W
16°W 16°W
17°W 17°W
59°N 59°N
58°N 58°N
57°N 57°N
56°N 56°N
55°N 55°N
54°N 54°N
53°N 53°N
52°N 52°N
51°N 51°N
Total_mac_23/4/07
500m 200m
Figure 3: 0407S – Total numbers of mackerel stage 1 eggs recorded.
0 0
3 1
2 8
0 2 8 1 0
5 3 2
4 7 0 0 1
3 1 0 0 0 0
0 1 8
0 0 0 0 0 0 0
0 0 2 0 0 0 8
5 1 1 1 0
0 0 1 2
0 0 0 0
7 4 2
2 5
0 0
0 1 1 0
0
5 5 8 6 1
0 1 0 5 1 5 0 0 0 0 0
0 0 0 0 2 6 4
4 4 3 2 0 0 0
0
0 0 0 0 0 0
34
12 59
29 81
28
12 18 16 38 21 24 68 16
58 10
12 68 77 25
39 64 20
85 96 16
23 34
39 13 34 69
21
15 20
12
170 104 124
169
103 164 175
136 169 115 154
483
5°W 5°W
6°W 6°W
7°W 7°W
8°W 8°W
9°W 9°W
10°W 10°W
11°W 11°W
12°W 12°W
13°W 13°W
14°W 14°W
15°W 15°W
16°W 16°W
17°W 17°W
59°N 59°N
58°N 58°N
57°N 57°N
56°N 56°N
55°N 55°N
54°N 54°N
53°N 53°N
52°N 52°N
51°N 51°N
mac1_23/4/07
500m 200m
Figure 4: 0407S – Total numbers of horse mackerel eggs recorded.
0 0
0 8 0
0 0 4 2 0 0 0 0 0
5 0 0 2 2 0 0 0
1 1 2 0 1
0 0 0 0 0 0
0 0 0 0 0 3 1
2 0 0 0 0 0
0 5 7 4 1 9 0
2 2 0 2 0 7
9 0 0 0 0
0 0 0 0 0 0 0 0 4 0 1 4
4 0 0
0 1 0 0 0
0 0 0 0
0 1
0 0 0 0 0
0
0 0 0 0 0 2 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0
0 0 0 0 0 0 0 0
0
0 0 0 0 0 0 0
36
15 38 43
14 21
13 11 25
316
5°W 5°W
6°W 6°W
7°W 7°W
8°W 8°W
9°W 9°W
10°W 10°W
11°W 11°W
12°W 12°W
13°W 13°W
14°W 14°W
15°W 15°W
16°W 16°W
17°W 17°W
59°N 59°N
58°N 58°N
57°N 57°N
56°N 56°N
55°N 55°N
54°N 54°N
53°N 53°N
52°N 52°N
51°N 51°N
hmac_23/4/07
500m 200m
Figure 5: 0407S – Total numbers of horse mackerel stage 1 eggs recorded.
0 0
0 2 0
0 0 1 0 0 0 0 0 0
3 0 0 0 0 0 0 0
1 0 0 0 0
5 0 0 0 0 0 0
0 0 0 0 0 1 0 6
0 2 0 0 0 0
0 3 2 1 1 0 9 7 0
1 1 0 0 0 3 2 3 7 0 0 0 0
0 0 0 0 0 0 0 0 3 0 1 0
1 0 0
0 0 0 0 0
0 0 0 0 1 0
0 0 0 0 0
0
0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0
0
0 0 0 0 0 0 0 0
0
0 0 0 0 0 0 0
18
23 19
137
5°W 5°W
6°W 6°W
7°W 7°W
8°W 8°W
9°W 9°W
10°W 10°W
11°W 11°W
12°W 12°W
13°W 13°W
14°W 14°W
15°W 15°W
16°W 16°W
17°W 17°W
59°N 59°N
58°N 58°N
57°N 57°N
56°N 56°N
55°N 55°N
54°N 54°N
53°N 53°N
52°N 52°N
51°N 51°N
hmac1_23/4/07
500m 200m
