1 FISP pollack introduction

Pollack represents an economically and socially important fishery across the UK. Recreational and commercial fishers have highlighted a decline in Pollack (Pollachius pollachius) across the English channel. ICES stock assessments have similarly indicated there is insufficient evidence to identify exploitation and population trends, however have highlighted a decline of 72% in commercial landings since 1968. Data collection is required on life history parameters, abundance and spatial ecology to ensure sustainability in commercial and recreational fisheries.

2 Commercial landings data

2.1 Plymouth

Between 2013 to 2023-11-06 the have been 1.8535^{4} tonnes of pollack landed commercially at Plymouth fish market. Of this, 46.29% of fish were landed during the spawning season (January until the end of March).

The weekly landings are from 2013 until 2023-11-06 are shown in figure 16.

Weekly Commercial landings of *P. pollachius* from the port of Plymouth from 2013 until 2023

Figure 1: Weekly Commercial landings of P. pollachius from the port of Plymouth from 2013 until 2023

Table 10 Summary of Plymouth landings data (kg) from 2013 until 2023-11-06

Year Landings Median_Landings SD_dev_Landings mean_Landings Max Min
2013 224318 2764.0 4366.495 4313.808 20578 5
2014 269637 2361.0 7103.199 5185.327 35038 148
2015 203025 2532.0 4444.819 4060.500 23743 98
2016 241277 3127.0 5374.556 4730.922 24270 435
2017 212363 3156.0 4528.336 4006.849 23670 120
2018 141751 1824.0 2656.790 2779.431 10925 179
2019 112927 1900.5 1524.737 2171.673 6017 152
2020 132183 1948.5 2671.949 2541.981 12042 33
2021 154434 1508.0 3693.129 2913.849 14834 0
2022 81503 1196.0 1814.586 1734.106 8615 0
2023 80077 699.0 2102.517 1404.860 12136 0

The landings of P. pollachius to Plymouth fish market decreased after 2016, before levelling out in 2020 and falling further since (Figure 17.). Although most of the landings occurred during the spawning season (January until March, Figure 18), the reduction in landings was driven by a reduction in the quantity of landings during these months (Figure 19.). However, the catches during the summer months increased slightly, which probably was driven by an increase in commercial rod and line fishing for the species when present on the inshore reef systems off Plymouth.

It is noted that landings are a poor proxy for biomass as they are susceptible to market forces and targeting preferences as well as stock biomass

2.2 Commercial landings Plymouth, Newlyn and Brixham 2008-2019

From 2008-2019 there were 7226.44 tonnes of P. pollachius landed in Newlyn, Brixham and Plymouth, worth £1.9085105^{7} at a mean Cost/kg of £2.64. The data is summarised in Table. 10.

Landings of *P. pollachius* from 2008-2019 by port

Figure 2: Landings of P. pollachius from 2008-2019 by port

Landings of *P. pollachius* from 2008-2019 by gear type

Figure 3: Landings of P. pollachius from 2008-2019 by gear type

Landings of *P. pollachius* from 2008-2019 by Vessel length

Figure 4: Landings of P. pollachius from 2008-2019 by Vessel length

Table 11 Summary of landings (tonnes) from Plymouth, Newlyn and Brixham from 2008-2019
Port Year Landings Median_Landings SD_dev_Landings mean_Landings Max Min
Brixham 2008 96.267 0.194 2.908 1.284 16.786 0.001
Brixham 2009 78.938 0.273 2.129 1.067 11.477 0.000
Brixham 2010 75.902 0.131 1.995 0.883 11.218 0.000
Brixham 2011 65.312 0.101 1.391 0.710 7.313 0.001
Brixham 2012 79.289 0.131 1.825 0.881 10.839 0.001
Brixham 2013 89.820 0.174 2.396 1.082 16.218 0.001
Brixham 2014 85.839 0.086 3.069 1.145 19.196 0.000
Brixham 2015 61.238 0.189 1.792 0.795 11.329 0.002
Brixham 2016 76.632 0.156 1.506 0.891 7.785 0.001
Brixham 2017 62.190 0.051 2.266 0.749 15.920 0.001
Brixham 2018 41.012 0.031 1.198 0.482 6.835 0.001
Brixham 2019 38.214 0.043 1.174 0.490 5.904 0.000
Newlyn 2008 582.561 0.525 19.278 6.774 104.121 0.003
Newlyn 2009 534.594 0.322 15.098 5.569 99.109 0.002
Newlyn 2010 441.058 0.391 14.485 5.012 103.938 0.001
Newlyn 2011 530.389 0.306 19.023 5.703 131.780 0.001
Newlyn 2012 470.951 0.604 13.392 5.292 92.430 0.002
Newlyn 2013 445.638 0.328 10.555 4.126 65.813 0.001
Newlyn 2014 545.796 0.591 15.489 5.998 95.884 0.001
Newlyn 2015 367.656 0.312 8.608 4.226 47.911 0.001
Newlyn 2016 579.425 0.525 15.424 5.737 98.663 0.002
Newlyn 2017 277.790 0.550 5.721 2.987 28.445 0.000
Newlyn 2018 263.450 0.638 5.286 2.864 33.340 0.001
Newlyn 2019 263.020 0.440 5.091 2.579 29.781 0.001
Plymouth 2008 97.377 0.191 3.839 1.411 21.982 0.001
Plymouth 2009 98.199 0.135 4.858 1.309 39.770 0.001
Plymouth 2010 76.843 0.142 2.783 0.817 21.924 0.001
Plymouth 2011 87.022 0.201 3.130 1.102 19.374 0.000
Plymouth 2012 87.122 0.171 2.453 0.990 17.177 0.001
Plymouth 2013 85.910 0.205 1.989 0.914 15.039 0.001
Plymouth 2014 111.116 0.204 3.469 1.307 21.977 0.001
Plymouth 2015 72.562 0.081 2.353 0.854 18.644 0.001
Plymouth 2016 94.111 0.068 2.988 1.001 19.966 0.001
Plymouth 2017 117.476 0.048 4.273 1.566 31.242 0.001
Plymouth 2018 74.292 0.024 1.858 0.884 9.150 0.001
Plymouth 2019 71.432 0.027 2.356 0.882 13.885 0.001

3 Recreational catches FISP pollack. Data summary

3.1 Catch, size and effort data

The pollack FISP project is a collaboration between charter skippers and scientists to address ongoing concerns of both the recreational and commercial fleet regarding the stock status for the species.14 skippers have already collected length data on 8750 pollack from 484 trips, this will allow the assessment of stock abundance, composition and recruitment. 20.85 % of pollack were returned alive.

The total catch during this time period was 16.85 tonnes of which 1.5 tonnes was returned alive.

The mean size of P. pollachius captured was 54.77 cm, equating to 3.21 years of age. The size distribution is shown in Figure ??) .

In 2023 there were 5358 pollack captured from 277 trips.This equates to 10.35 tonnes of fish. The mean size of P. pollachius captured during 2023 was 54.47 cm, equating to 3.2 years of age.

During the 2023 spawning period (January to the end of April) there were 1146 pollack captured from 64 trips.There were 2.29 tonnes of pollack caught during this period with a mean size of 54.13 cm, equating to 3.26 years of age.

From the first of May until June 30th there were 3276 pollack captured from 141 trips.There were 6.44 tonnes of pollack caught during this period with a mean size of 54.81 cm, equating to 3.23 years of age.There were 49 otoliths collected from 24 fish.

From the first of July until September 30th there were 736 pollack captured from 64 trips.There were 1.38 tonnes of pollack caught during this period with a mean size of 55.45 cm, equating to 3.22 years of age.There were 67 otoliths collected from 34 fish.There were 9 sampling trips. The direct value of the P. pollachius fishery to the 14 skippers, during this period is £112800 equating to £87/ kg.

There have been 174 otoliths collected from 87 fish as of 2023-11-06.

The direct value of the P. pollachius fishery to the 14 skippers, as of 2023-11-06 is £387200 equating to £26.8/ kg. This is an approximate direct value and does not account for indirect value such as accommodation, tackle, fuel and food for the anglers.

Month Median SD_dev Mean Max Min
1 11.72 17.57 20.09 50.64 5.82
2 24.57 26.20 28.67 88.74 0.00
3 22.82 52.03 45.89 151.00 0.00
4 26.82 47.10 36.33 275.05 0.00
5 36.13 33.01 43.64 167.14 0.00
6 31.55 48.92 43.62 374.92 0.00
7 17.33 27.31 25.25 156.22 0.28
8 14.89 16.30 19.77 69.77 0.21
9 12.14 18.68 16.73 101.99 0.00
10 25.06 16.55 26.80 70.67 10.51
11 12.73 26.46 21.24 66.49 0.22
12 4.79 5.12 4.93 13.25 0.61

3.1.1 Catch Per Unit Effort

Raw Catch Per Unit Effort (median Kg/ Trip) showed an increasing trend during February, which was sustained until June when catches decreased during the summer months. The raw median CPUE per trip peaked in March with a nadir in August (Figure 5.). The adjusted CPUE (Kg/trip/time spent targeting P. pollachius) peaked in March, with a nadir in September (Figure 6.).Correcting for numbers of anglers produced confusing results, as the relationship between angler numbers and catches is non-linear, due to disturbance of the shoal by additional fishing gear.

Table. 3 Adjusted CPUE (Kg/Trip/Angler) per month

Month CPUE Confint Upper Lower
1 3.93 1.59 5.52 2.35
2 4.16 3.17 7.33 0.98
3 5.27 4.45 9.72 0.83
4 4.39 2.60 6.99 1.79
5 4.73 2.76 7.49 1.98
6 5.53 2.17 7.70 3.36
7 3.94 1.84 5.77 2.10
8 3.51 0.94 4.44 2.57
9 2.41 1.00 3.42 1.41
10 3.58 1.69 5.26 1.89
11 1.72 2.01 3.73 -0.30
12 0.75 2.34 3.09 -1.59
Raw median monthly CPUE (Kg/Trips). Ribbon indicates 95% confidence intervals.

Figure 5: Raw median monthly CPUE (Kg/Trips). Ribbon indicates 95% confidence intervals.

Figure 8. Median CPUE (Kg/ trip) adjusted for fishing time spent targeting *P. pollachius* . Ribbon indicates 95% confidence intervals

Figure 6: Figure 8. Median CPUE (Kg/ trip) adjusted for fishing time spent targeting P. pollachius . Ribbon indicates 95% confidence intervals

3.1.2 Yearly Catch Per Unit Effort

Histogram of Catch Per Unit Effort per trip between years.Red line indicates theoretical normal distribution

Figure 7: Histogram of Catch Per Unit Effort per trip between years.Red line indicates theoretical normal distribution

Box plot comparison of mean CPUE (Kg/ trip) between years. Text indicate mean CPUE values

Figure 8: Box plot comparison of mean CPUE (Kg/ trip) between years. Text indicate mean CPUE values