General information
The capelin is a small pelagic schooling fish. It is a cold-water species that inhabits arctic and subarctic waters in the North Atlantic and North Pacific. Capelin in the Iceland-East Greenland-Jan Mayen area is considered to be a single stock, and is denoted here after as the IEGJM capelin stock.
Fisheries of capelin began in Iceland in the mid-1960s. Besides being commercially important capelin is a key species in the marine ecosystem off Iceland. It feeds on small zooplankton, especially copepods but also amphipods and krill, but is itself an important food for cod, saithe, haddock, halibut and other commercial fish. It is also important prey for whales and birds. Thus, capelin is an important link in the transfer of energy and nutrients to the upper levels of the food web. Preferred temperature for capelin is usually 1-3°C during feeding migration and it is then often at the southern extent of cold Arctic water. When the adult capelin migrates from the feeding areas far north of Iceland, it is mainly considered to enter the continental shelf north of Iceland and then migrate clockwise around the island. Part of the main migration continues all the way towards the coast west of Iceland. Spawning takes place in shallow water in March-April in relatively warm seas south and southwest coast of the country. Spawning has also been observed in coastal areas north of Iceland but the extent of that spawning has been considered small compared to the number that spawns in the south. The majority of capelin dies after spawning, usually at the age of 3 years, although mostly females may survive spawning (Christiansen et al., 2008). The migrations of capelin contribute to a huge transfer of energy into the ecosystem of the Icelandic continental shelf. Larvae and juveniles drift clockwise along the continental shelf north and east of Iceland and in variable quantities towards Denmark Strait and to the shelf of East Greenland. Nursery grounds of capelin are in the waters north of Iceland and increasingly on the continental shelf of East Greenland (Bardarson et al., 2021) since early 2000s.
Fisheries
No fisheries on the IEGJM capelin stock took place in the 2023/2024 fishing season. Total historical catch of the stock is shown in Figure 1 and distribution of the catches of the Icelandic fishing fleet by season can be seen on Figure 2.
Changes in fishing technology and fishing patterns
There were no catches in 2023/24. Historically, most of the catches has been taken in purse seine but a variable amount has been taken with pelagic trawl through the fishing seasons, related to the size of the TAC and when it is issued. Discards have been considered negligible.
Stock assessment
Capelin acoustic assessment surveys
The IEGJM capelin stock has been assessed by acoustics annually since 1978. The surveys have been conducted in autumn (September-December) and in winter (January-February). An overview is given in the Northwestern Working Group NWWG, ICES stock annex.
Autumn survey 2024
The Autumn survey was conducted with the aim of assessing both the immature and the maturing part of the stock (Bardarson et al., 2024). Since 2010, the autumn surveys have started in September (and partly in late August), a month earlier than in the preceding years because of difficulties in covering the stock due to drift ice and weather during later months at the more north-westerly feeding grounds of the stock since early 2000s (Vilhjálmsson, 2007).
The survey was conducted on the behalf of MFRI by the r/v Arni Fridriksson until replaced by the f/v Polar Ammassak (due to engine failure of r/v Arni) and r/v Tarajoq on behalf of GINR (Greenland Institute of Natural Resources) (Figure 3). The survey area was on and along the shelf edge off East Greenland from about 64°30´N towards about 72°15´N, also covering the Denmark Strait and the slope off northwest Iceland. The Iceland Sea and Kolbeinsey ridge were only briefly scouted due to time constraints and for same reason hydrographic measurements and zooplankton sampling were limited compared to previous years. There were also delays due to bad weather.
In general, drift ice did not limit the coverage of the survey vessels although icebergs and a lack of information on bottom topography occasionally affected routes and limited the extent of transects towards the Greenlandic coast (Figure 3).
Maturing capelin was mainly observed outside the Icelandic continental shelf North and Northwest of the Westfjords in Iceland (Figure 4). In the western Denmark Strait maturing capelin was mixed with immature capelin, while mainly maturing capelin was found further east. Similar as last year, the distribution of mature capelin reached only a relatively short distance east of Denmark Strait and that is again a drastic change from observations in autumn 2022, when mature capelin was found on or along the East Greenland continental shelf south, east and north of Scoresby Sound. Further, no capelin was found near the western part of the Jan Mayen ridge or at the Kolbeinsey ridge. In general, there were no signs of significant quantities of capelin east of Kolbeinsey ridge nor along Icelandic shelf edges. Juveniles (0-group) of various species, including capelin (although not quantified) were observed along the continental shelf north and northwest of Iceland and along the southwestern coverage of the Greenlandic shelf. Immature capelin was found along the Greenlandic shelf, dominating in southwestern part of the survey area and Denmark Strait (Figure 4).
The total biomass estimate was 624 722 tonnes. Table 3 in the annexe gives information on the age-disaggregated numbers and biomass of the capelin stock components.
Historical trend of mean weight of 1 and 2 year old capelin during autumn survey is shown in Figure 5.
Surveys in winter 2024/2025
Winter surveys were conducted from December 2024 to February 2025. The main objective of the surveys was to assess the maturing part of the stock using acoustic stock assessment accompanied with pelagic trawl sampling. This was a coordinated collaboration between one Icelandic research vessel and several Icelandic and Greenlandic fishing vessels. Scientists from MFRI were on board each vessel during the main surveys in January and February, oversaw and interpreted the acoustic measurements. All the participating vessels, had calibrated echo sounders, generally performed shortly before the surveys.
December 2024
The first winter survey was conducted in December 2024 with the participation of the fishing vessel Aðalsteinn Jónsson (Figure 6). It was proposed by Fisheries Iceland and considered to be of value by MFRI. Its goal was to assess the distribution of capelin during the early stages of the migration and evaluate how far south and east they were distributed for planning the measurement of the whole stock in January. Therefore, this survey was not used in the stock assessment. The survey was limited due to bad weather conditions; few capelin schools were observed. Around 30 000 t of spawning stock biomass was estimated and mainly found over the Kolbeinsey ridge.
January 2025
The second winter survey was conducted from 15 to 28 January 2025 on the r/v Árni Fríðriksson and the f/v Barði, Heimaey, and Polar Ammassak (Figure 7). The survey tracks were design to cover three strata, centered on the east, north, and northwest of Iceland. During the survey, the majority of mature capelin were found in the northeast and east of Iceland (Figure 7). The capelin found furthest northwest of Iceland were juveniles. The spawning stock biomass was estimated to be 180 000 t in the east and 50 000 t in the west. Table 4 in annex gives information of the age disaggregated numbers and biomass of the capelin stock components.
A third winter survey was conducted in the east and southeast of Iceland by the fishing vessels Polar Ammassak and Aðalsteinn Jónsson from 27 to 31 of January (Figure 8). The two independent searches were designed crisscrossing each other with the goal of double-checking the first January acoustic measurements. This survey was proposed by Fisheries Iceland and it was the view of MFRI that it could give valuable scientific information.
These measurements were conducted against the capelin migration (Figure 8) and the estimate of mature capelin was found to be in lower (130 000 t) than in the earlier January survey (from 15 to 28 of January, Figure 7). The survey area was more constrained than in the more comprehensive earlier survey. Furthermore, there were indications for capelin being outside of the survey domain (exploration by Polar Ammassak outside Mjóifjörður and Norðfjörður). No capelin samples were collected in this coverage. Therefore, MFRI considered that this survey failed to cover the whole capelin stock in the east, and the measurements earlier in January were more appropriate for assessment of the stock.
February 2025
A fourth winter survey was done from 8 to 19 February (Figure 9) on the r/v Árni Fríðriksson and the f/v Heimaey and Polar Ammassak. The main objective of this survey was to assess if more capelin had migrated from north, or from within the sea ice into the survey domain northwest and north of Iceland (Figure 9). Mature capelin was found mainly north and northwest of Iceland and the spawning stock biomass was estimated to be 98 200 tonnes. This estimate indicates that more capelin had entered into the area than measured in January (when 50 000 t were measured in the area), and MFRI considered it to give more representative measure of the stock size and should be used for assessment. Table 5 in annex gives information of the age disaggregated numbers and biomass of the capelin stock components.
A fifth survey, which as proposed by Fisheries Iceland and agreed to participate by MFRI, had similar objective as the fourth survey to assess if more capelin had entered the survey domain northwest of Iceland. It took place during 24 to 28 of February (Figure 10) on the f/v Aðalsteinn Jónsson and Polar Ammassak. The measurements amounted to 75 000 of mature capelin, so there was no signs of more capelin entering the area. This survey had a coarser design because of a short weather window to cover the Denmark Strait region which could indicate that the coverage was not sufficient for assessing the capelin abundance in the area. Hence, the results were not used in the estimate of the stock size.
Considering the information provided above, the final winter estimate of the maturing, or the fishable stock, derived from the first January survey for the capelin in the eastern part (Figure 7) and early February for the western part (Figure 10). It resulted in 278 000 t total (Spawning Stock Biomass(SSB) = 180 000 t and 98 200 t, respectively).
Predation model results and resulting advice
Following completion of surveys estimations of stock parameters and their uncertainty 100 thousand bootstrap replicates were used as starting values for predation model runs. Results from the predation model runs are given in Table 1 and shown in Figure 12 and Figure 13.
| mean | 5% | 25% | 50% | 75% | 95% | |
|---|---|---|---|---|---|---|
| SSB | 184.37 | 114.00 | 151.01 | 180.71 | 213.77 | 267.19 |
| Predation | 98.89 | 65.93 | 82.72 | 96.58 | 112.66 | 139.47 |
The model (ICES 2023a, ICES 2023b) is designed to cover predation on the main spawning migration of capelin. A schematic description of the model is in Figure 11.
The predation model (ICES 2023a, ICES 2023b) applies to the stock component that migrates the clockwise route around Iceland. In most years, majority of the stock has migrated that route and nearly all the catches have been taken from that component. All the capelin stock is assumed to be in the east on 15th of January, and on 15th of March, it is assumed that all the capelin stock spawns in the south and southwest, a higher proportion in the southwest. The predators (cod, haddock and saithe) are assumed to be stationary during the period of capelin migration and their spatial distribution is obtained from the demersal survey in March from 1985 to the previous year. The total abundance of each predator is predictions for the current year based on assessment in previous year.
The fish stock size is based on combination of autumn (weighted 1/3) and winter measurements (weighted 2/3), both of which are considered to have covered the stock’s distribution area. The results of these measurements were similar. The winter measurement is based on the results of January surveys for the area east of Kolbeinsey Ridge (CV=0.36) and February surveys for the western area (CV=0.33) (Table 2). The January winter survey had a lower SSB estimates than the autumn survey. However, repeated survey in February showed the arrival of an additional component of mature capelin. Hence the stock estimates from the last two complete winter surveys (January and February) were used along with the autumn survey estimate to predict the status and development of the capelin stock (i.a. the starting values of the predation model).
Note that, it was necessary to revise the calibration of one of the participating vessels in the autumn survey (Polar Ammassak) after the last advice was published in October 2024.This led to an upward revision of the estimated fishable biomass by 10 000 tonnes. This correction would not have led to a change in the intermedia advice given in October 2024.
Management plans and evaluations
Methods
The objective of the HCR for the stock is to leave at least 114 000 tonnes (= \(B_{lim}\) ) for spawning (escapement strategy). The initial (preliminary), intermediate and final TACs are based on acoustic surveys.
a) The initial TAC advice for the subsequent fishing season is issued by ICES in June. It is based on the autumn survey abundance estimate of immature capelin.
b) The intermediate TAC advice is issued by MFRI in autumn based on the biomass estimate of maturing capelin.
c) The final TAC advice is issued by MFRI in January/February based on the biomass estimate of maturing capelin.
The initial (preliminary) quota follows a simple forecast that is based on a linear relation between historic observations of the abundance of juveniles from the acoustic autumn surveys and the corresponding final TACs nearly 1½ year later. Based on this rule, advice on the initial quota for the fishing season 2024/25 is given.
The intermediate and final TACs are set so that there is at least 95% probability that there will be at least 114 000 tonnes (= \(B_{lim}\) ) of mature capelin left for spawning at the spawning time (15 March). This was done for the first time in 2015/2016 by the Icelandic Marine Research Institute and was not evaluated by ICES.
The estimated SSB at spawning time (March-April) has been recompiled for 1981-2023 (Figure 14), using the model adopted in 2015 and 2023, i.e taking into account uncertainty in the acoustic measurements and using the predation model adopted in 2015. Uncertainty in acoustic measurements was recompiled for the years 2002-2006 and 2012-2014 by recalculating the acoustic indices and bootstrapping the results. Additionally, uncertainty was available for the years since 2015 when the advice has been given based on the new HCR. For earlier years the CV in the acoustic measurements was estimated by looking at survey reports as well as text from (Vilhjálmsson, 1994). The estimated CV was in the range of 0.15-0.25 and was included as a lognormal multiplier on available average values from the same sources.
These methods were endorsed by the benchmark working group WKICE in 2015 and WKCAPELIN 2022 with minor adjustments. See WKICE (ICES, 2015), WKCAPELIN (ICES, 2023b) and the Stock Annex for the capelin in the IEGJM area. Previously, (since early 1980s) the stock was managed according to an escapement strategy, leaving 400 000 tonnes for spawning (uncertainty of the estimates were not considered). To predict the TAC for the next fishing season a model was developed in the early 1990s (Gudmundsdottir and Vilhjalmsson, 2002). These models were not endorsed by the benchmark working group WKSHORT 2009.
Reference points
During WKICE, a \(B_{lim}\) of 150 000 tonnes was defined (ICES, 2015) and following WKCAPELIN \(B_{lim}\) was changed to 114 000 tonnes. No other reference points are defined for this stock.
State of the stock
The fishable stock was estimated to 318 000 tonnes in October 2024 and 278 000 tonnes in January /February 2025. The predation model (ICES, 2015), accounting for catches (in this case winter catch of 8 589 t) and predation between surveys and spawning by cod, saithe and haddock, estimated SSB to 180 710 tonnes which were left for spawning in spring 2025 (Table 1). Given the uncertainty estimates, there was 95% probability that at least 114 000 tonnes was left for spawning, if the catches taken amounted to 8 589 tonnes, which represents the final fishing for capelin in the fishing year 2024/2025. The acoustic estimate of immature capelin from the autumn survey in October 2024 was 58.5 billion. An initial advice for the fishing season 2025/26 on basis of that amount will be issued by ICES in June 2025.
Uncertainties in assessment and forecast
The uncertainty of the assessment and forecast depends largely on the quality of the acoustic surveys in terms of coverage, conditions for acoustic measurements and the aggregation (high patchiness leads to high variance) of the capelin.
The uncertainty is estimated by bootstrapping (see WKICE). The CV for the immature abundance was estimated to 0.15 in the 2024 autumn survey. The CV for the mature biomass was estimated to 0.25 in the 2024 autumn survey. In the two winter surveys in January (for the area east of Kolbeinsey Ridge) and February (for the western area) used for the assessment in 2025 the CV was 0.36 and 0.33, respectively.
While the autumn survey was effected by time constrains the distribution of immature and mature components of the capelin stock seemed to have been covered. The final estimate was based on combination of the autumn survey and two winter surveys in January and February. The winter surveys had considerably lower SSB estimates than the autumn survey.
Although the final winter estimate of the fishable biomass derived from two different surveys conducted one month a part, it is not considerable to add uncertainty to the assessment. It is because that considering the migration route of the stock, capelin in the east measured in January were for sure not measured again in the west in February. Furthermore, these were the most comprehensive measurements of capelin in these two areas of all the surveys conduced.
During the surveys, some components of the stock are likely to have been measured with the survey migration and others against it, and that can add bias and uncertainty to the estimates to unquantifiable degree.
Comparison with previous assessment and forecast.
For the fishing season 2024/2025, the initial quota and intermediate advise was 0 t while the final advice TAC was set to not more than 8 589 tonnes.
Management considerations
The fishing season for capelin has since 1975 started in the period from late June to July/August when surveys on the juvenile part of the stock the year before have resulted in the setting of an initial (preliminary) catch quota. During summer, the availability of plankton is at its highest and the fishable stock of capelin is feeding very actively over large areas between Iceland, Greenland and Jan Mayen, increasing rapidly in length, weight and fat content. By late September/beginning of October this period of rapid growth is over. The growth is fastest the first two years, but the weight increase is highest in the year before spawning (Vilhjálmsson, 1994).
Given the large weight increase in the summer before spawning it is likely that there will be more biomass of maturing fish in autumn than in summer, even though the level of natural mortality is not well known during this time period. This should be considered for optimal timing of fishery in relation to yield and ecological impact. This is also supported by information for the Barents Sea capelin where it has been shown that fishing during autumn would maximize the yield, but from the ecosystem point of view a winter fishery were preferable (Gjøsæter et al., 2002). As the biology and role in the ecosystem of these two capelin stocks are similar, this is considered to be valid for the capelin in the Iceland-East Greenland-Jan Mayen area as well - until it is studied for this specific stock.
During the autumn surveys, juvenile and adult capelin is often found together. This should be considered during summer and autumn fishing because the survival rate of juvenile capelin that escapes through the trawl net is unknown.
Ecosystem considerations
Capelin is an important forage fish and its dynamics are expected to have implications on the productivity of their predators.
The importance of capelin in East Greenlandic waters is not well documented but effort has been increased considerably during autumn surveys towards evaluation of capelin role in the ecosystem e.g. by research on feeding of capelin, estimates of prey availability, predators’ distributions and environmental monitoring.
In Icelandic waters, capelin is the main single item in the diet of Icelandic cod, a key prey to several species of marine mammals and seabirds and also important as food for several other commercial fish species (see e.g. Vilhjálmsson, 2002, Singh et al., 2023).
Regulations and their effects
Over the years, the fishery has been closed during April–late June and the season has started in July/August or later, depending on the state of the stock.
Areas with high abundances of juvenile age 1 and 2 capelin (on the shelf region off NW-, N- and NE-Iceland) have usually been closed to the summer and autumn fishery.
It is permissible to transfer catches from the purse seine of one vessel to another vessel, in order to avoid slippage. However, if the catches are beyond the carrying capacity of the vessel and no other vessel is nearby, slippage is allowed. In recent years, reporting of such slippage has not been frequent. Industrial trawlers do not have the permission to slip capelin in order to harmonize catches to the processing.
In Icelandic waters, fishing with pelagic trawl is only allowed in limited area off the NE-coast (fishing in January) to protect juvenile capelin and to reduce the risk of affecting the spawning migration route (shuttering of migrating capelin schools by pelagic trawling has been hypothesized).
As a precautionary measure to protect juvenile capelin, the coastal states (Iceland, Greenland and Norway) have agreed that from 2021 fishing shall not start until 15. October.
References
Anon. 2015. Agreed Record of Conclusions of Coastal State consultations on the management of the capelin stock in the Iceland–East Greenland–Jan Mayen area. Reykjavík, Iceland. 7–8 May 2015. https://www.regjeringen.no/contentassets/37b66bdf33d84e99924bb27553641719/samledokument-lodde-mai-2015—agreed-records—bilateral-avtale.pdf. Last accessed: 17 November 2022.
Bardarson, B, Heilman, L, Jonsson, SÞ and Jansen, T 2024. Cruise report of acoustic assessment of the Iceland-East Greenland-Jan Mayen capelin stock in the autumn 2024. Kver Hafrannsóknastofnunar. KV2024-10. 18 pp.
Bardarson, B, Gudnason, K, Singh, W, Petursdottir, H, & Jonsson, SÞ (2021). Loðna (Mallotus villosus). Haf- Og Vatnarannsoknir, HV 2021(14), 31–34.
Christiansen, JS, Præbel, K, Siikavuopio, SI, Carscadden, JE 2008. Facultative semelparity in capelin Mallotus villosus (Osmeridae)-an experimental test of a life history phenomenon in a sub-arctic fish, Journal of Experimental Marine Biology and Ecology, Volume 360, Issue 1, 2008, Pages 47-55, ISSN 0022-0981, https://doi.org/10.1016/j.jembe.2008.04.003.
Engilbertsson, V, Óskarsson, GJ and Marteinsdóttir, G (2012). Inter-annual Variation in Fat Content of the Icelandic Capelin. ICES CM 2013/N:26.
Gjøsæter, H, Bogstad, B, and Tjelmeland, S 2002. Assessment methodology for Barents Sea capelin, Mallotus villosus (Müller). – ICES Journal of Marine Science, 59: 1086–1095.
Gudmundsdottir, A, and Vilhjalmsson, H 2002. Predicting Total Allowable Catches for Icelandic capelin, 1978–2001. ICES Journal of Marine Science, 59: 1105–1115.
Gudmundsdottir, A, and Sigurdsson, Th 2014. Growth of capelin in the Iceland-East Greenland-Jan Mayen area. NWWG 2014/WD:29.
ICES. 2015. Report of the Benchmark Workshop on Icelandic Stocks (WKICE), 26-30 January, 2015. ICES Headquarters. ICES CM 2015/ACOM:31.
ICES. 2023. Benchmark workshop on capelin (WKCAPELIN). ICES Scientific Reports. 5:62. 282 pp. https://doi.org/ices.pub.23260388
ICES 2024. Capelin (Mallotus villosus) in subareas 5 and 14 and Division 2.a west of 5°W (Iceland and Faroes grounds, East Greenland, Jan Mayen area). ICES Advice: Recurrent Advice. Report. https://doi.org/10.17895/ices.advice.25663980.v1
Jansen, T, Hansen, FT, Bardarson, B 2021. Larval drift dynamics, thermal conditions and the shift in juvenile capelin distribution and recruitment success around Iceland and East Greenland. Fisheries Research, 236.
MFRI. 2024. State of Marine Stocks and Advice 2024, advice on capelin. Marine and Freshwater Research Institute, 11 October 2024.
Singh, W, Ólafsdóttir, AH, Jónsson, SÞ, Óskarsson, GJ 2023. Capelin in a changing environment. Haf- og vatnarannsóknir, HV 2023-43. https://www.hafogvatn.is/static/research/files/capelin_2023_eng.pdf
Vilhjalmsson, H 1994. The Icelandic capelin stock. Capelin, Mallotus villosus (Müller), in the Iceland– Greenland–Jan Mayen area. Rit Fiskideildar, 13: 281 pp.
Vilhjálmsson, H 2002. Capelin (Mallotus villosus) in the Iceland–East Greenland–Jan Mayen ecosystem. ICES Journal of Marine Science: Journal du Conseil, 59: 870–883.
Vilhjálmsson, H 2007. Impact of changes in natural conditions on ocean resources. Law, science and ocean management 11, 225.
Tables
| Length | age1 | age2 | age3 | age4 | Total Number | Total Biomass (tonnes) |
|---|---|---|---|---|---|---|
| 8.5 | 732 | 0 | 0 | 0 | 732 | 1551 |
| 9 | 2506 | 0 | 0 | 0 | 2506 | 6651 |
| 9.5 | 6544 | 0 | 0 | 0 | 6544 | 21177 |
| 10 | 10263 | 0 | 0 | 0 | 10263 | 38412 |
| 10.5 | 10947 | 0 | 0 | 0 | 10947 | 47360 |
| 11 | 7424 | 0 | 0 | 0 | 7424 | 36682 |
| 11.5 | 5555 | 0 | 0 | 0 | 5555 | 32184 |
| 12 | 5990 | 0 | 0 | 0 | 5990 | 39622 |
| 12.5 | 2834 | 138 | 0 | 0 | 2972 | 22260 |
| 13 | 2203 | 130 | 0 | 0 | 2334 | 19963 |
| 13.5 | 1381 | 310 | 0 | 0 | 1691 | 16254 |
| 14 | 891 | 785 | 49 | 0 | 1725 | 18679 |
| 14.5 | 457 | 1043 | 89 | 0 | 1589 | 20307 |
| 15 | 0 | 1727 | 0 | 0 | 1727 | 24940 |
| 15.5 | 49 | 1678 | 49 | 0 | 1776 | 28316 |
| 16 | 0 | 1513 | 81 | 0 | 1594 | 28871 |
| 16.5 | 0 | 2269 | 81 | 0 | 2350 | 46868 |
| 17 | 0 | 1955 | 191 | 0 | 2146 | 47007 |
| 17.5 | 0 | 1805 | 127 | 130 | 2063 | 50780 |
| 18 | 0 | 1107 | 127 | 32 | 1266 | 33371 |
| 18.5 | 0 | 640 | 64 | 64 | 768 | 22299 |
| 19 | 0 | 255 | 49 | 32 | 336 | 10505 |
| 19.5 | 0 | 127 | 64 | 99 | 290 | 8857 |
| 20 | 0 | 0 | 49 | 0 | 49 | 1809 |
| Length | age2 | age3 | age4 | age5 | Total Number | Total Biomass (tonnes) |
|---|---|---|---|---|---|---|
| 8.5 | 74 | 5 | 0 | 0 | 80 | 160 |
| 9 | 398 | 0 | 0 | 0 | 398 | 1001 |
| 9.5 | 339 | 0 | 0 | 0 | 339 | 1075 |
| 10 | 673 | 0 | 0 | 0 | 673 | 2372 |
| 10.5 | 1021 | 0 | 0 | 0 | 1021 | 4127 |
| 11 | 1416 | 0 | 0 | 0 | 1416 | 6798 |
| 11.5 | 1195 | 0 | 0 | 0 | 1195 | 6705 |
| 12 | 1943 | 3 | 0 | 0 | 1946 | 12325 |
| 12.5 | 1118 | 33 | 0 | 0 | 1151 | 8507 |
| 13 | 969 | 3 | 33 | 0 | 1005 | 8304 |
| 13.5 | 882 | 78 | 0 | 0 | 960 | 9036 |
| 14 | 461 | 230 | 0 | 0 | 691 | 7575 |
| 14.5 | 235 | 429 | 0 | 0 | 664 | 8327 |
| 15 | 237 | 642 | 42 | 0 | 921 | 12796 |
| 15.5 | 38 | 945 | 0 | 0 | 983 | 15715 |
| 16 | 13 | 983 | 22 | 0 | 1018 | 18346 |
| 16.5 | 73 | 1467 | 35 | 0 | 1574 | 31573 |
| 17 | 0 | 1508 | 211 | 0 | 1718 | 38842 |
| 17.5 | 0 | 1061 | 177 | 0 | 1238 | 31362 |
| 18 | 0 | 1261 | 165 | 0 | 1427 | 39999 |
| 18.5 | 0 | 815 | 69 | 46 | 930 | 28600 |
| 19 | 0 | 373 | 6 | 0 | 380 | 12314 |
| 19.5 | 0 | 108 | 13 | 0 | 120 | 3969 |
| 20 | 0 | 28 | 3 | 0 | 31 | 1159 |
| Length | age2 | age3 | age4 | Total Number | Total Biomass (tonnes) |
|---|---|---|---|---|---|
| 8.5 | 13 | 0 | 0 | 13 | 21 |
| 9 | 13 | 0 | 0 | 13 | 23 |
| 9.5 | 38 | 0 | 0 | 38 | 102 |
| 10 | 128 | 0 | 0 | 128 | 382 |
| 10.5 | 192 | 0 | 0 | 192 | 677 |
| 11 | 244 | 0 | 0 | 244 | 1002 |
| 11.5 | 349 | 0 | 0 | 349 | 1696 |
| 12 | 467 | 0 | 0 | 467 | 2609 |
| 12.5 | 634 | 13 | 0 | 647 | 4152 |
| 13 | 490 | 0 | 0 | 490 | 3565 |
| 13.5 | 560 | 28 | 0 | 588 | 4917 |
| 14 | 275 | 87 | 0 | 362 | 3637 |
| 14.5 | 190 | 105 | 0 | 295 | 3325 |
| 15 | 270 | 129 | 8 | 406 | 5323 |
| 15.5 | 172 | 216 | 23 | 411 | 6008 |
| 16 | 69 | 450 | 36 | 555 | 9077 |
| 16.5 | 72 | 583 | 23 | 679 | 12219 |
| 17 | 72 | 519 | 64 | 655 | 13051 |
| 17.5 | 8 | 581 | 90 | 679 | 15411 |
| 18 | 13 | 352 | 46 | 411 | 10525 |
| 18.5 | 0 | 383 | 39 | 422 | 11707 |
| 19 | 0 | 175 | 23 | 198 | 6043 |
| 19.5 | 0 | 129 | 15 | 144 | 4822 |
| 20 | 0 | 67 | 15 | 82 | 2945 |