SHRIMP IN ÍSAFJARÐARDJÚP

Pandalus borealis


Assessment report
Published by

Marine and Freshwater Research Institute, Iceland

Published

17 October 2024

The fishery

Shrimp fishing started in Ísafjarðardjúp in the 1930‘s. The catch fluctuated between 1000 and 3100 tonnes between 1978 and 2002. No fishing was allowed in 2003-2010 due to low biomass indices, but since 2011 annual catches have been between 300 and 1100 tonnes (Figure 1). CPUE increased slowly between 1978 and 2003. However, since 2011 CPUE has been higher compared with the years before the closure, mainly due to increased density of shrimp within the innermost part of the fjord.

Figure 1: Shrimp in Ísafjarðardjúp. Total catch and catch per unit effort.

The distribution of the fishery has varied over time (Figure 2). From 2012-2017, there have been two main fishing areas; at the innermost part of the fjord and the outermost part. Since 2016, most of the catch has been caught at the innermost part of the fjord.

Figure 2: Shrimp in Ísafjarðardjúp. Spatial distribution of catch.

Survey data

The annual Icelandic shrimp survey has been conducted in the autumn since 1988 in Ísafjarðardjúp. The 2024 survey was conducted on 21 - 27 September 2024 and included 28 fixed and 15 random stations at depths of 34-125 m. Information on sampling procedure can be found in the manual ‘Handbók um stofnmælingu rækju 2024’ (Jónsdóttir 2024).

From 1988, shrimp was found within the inner part of the fjord as well as in Jökulfirðir. Following the decrease in the biomass index, the distributional area of shrimp decreased (Figure 3). Since 2011, shrimp has been found within a small area at the innermost part of the fjord and in less density at the outermost part of the fjord. In 2024, shrimp was found almost exclusively at the innermost part of the fjord.

Figure 3: Shrimp in Ísafjarðardjúp. Distribution and abundance in the annual shrimp survey. X denotes stations where no shrimp was found.

Indices

Four indices are used to assess the state of the offshore shrimp stock: total biomass, fishable biomass, female biomass, and juvenile biomass. Juveniles include all individuals equal to and below 13 mm carapace length, while the fishable biomass include all individuals equal to and above 15.5 mm carapace length. The fishable biomass index is used for calculation of the advice. Individuals between 13 and 15.5 mm carapace length are divided between the juvenile and fishable biomass indices. The female biomass includes all females and is defined as the spawning stock biomass.

All the indices, except the juvenile index, gradually decreased from 1990 to 2004 when they were at historically low levels (Figure 4). In 2011, the indices increased and fluctuated for three years. Since 2013 the indices have decreased but have been relatively stable from 2018 to 2022, with the exception of 2021, and the fishable index was above the reference level where the state of the stock is considered critical. The fishable index value of 20% of the mean of the three highest indices (Ilim) is used as a proxy for Blim. The fishable index was slihtly higher in 2024 compared to 2023, but below the reference level.

Figure 4: Shrimp in Ísafjarðardjúp. Stock biomass index, fishable biomass index, female biomass index and juvenile biomass index. The horizontal line indicates a Ilim which is a proxy for Blim (20% of the mean of the three highest indices).

Length distribution

In 2024, both male and female length distribution were below average (Figure 5).

Figure 5: Shrimp in Ísafjarðardjúp. Length distribution. The black line indicates males and the red line females. The grey area is the mean length distribution of both sexes for the whole study period.

Abundance of Atlantic cod and haddock

0-group cod and haddock indices have fluctuated throughout the study period. In 2024, the number of 0-group cod and haddock were low (Figure 6). Cod abundance (1 year and older) fluctuated between 1994 and 2010. In 2011 it increased and was in general at higher levels compared with before 2011. Cod abundance was low in 2024. Haddock abundance index increased steadily in 1995-2005 and has since then fluctuated at higher levels (Figure 6). In 2020-2021, haddock abundance was the highest observed in the study period but decreased in 2022-2024, but is still high when viewed in the long term perspective.

Figure 6: Cod and haddock in Ísafjarðardjúp. Abundance indices in the annual shrimp survey.

Distribution of haddock has increased following higher haddock biomass in Ísafjarðardjúp (Figure 7). In 1988-2000 haddock was mainly found at the outer part of the fjord, but since 2003 the distributional area has increased, and it has been found in the whole fjord.

Figure 7: Haddock in Ísafjarðardjúp. Distribution of haddock in the annual shrimp survey.

Temperature

Mean surface and bottom temperature increased from 1988 to 2023 (Figure 8). The temperature remained relatively high until after 2010 that it decreased again. Since 2015, the mean surface and bottom temperature have mainly remained between 7 and 8.5°C except in 2022 when it was higher.

Figure 8: Temperature. Mean surface temperature (red) and bottom temperature (black) in Ísafjarðardjúp during the shrimp survey.

Management

The Ministry of Food, Agriculture and Fisheries is responsible for management of the Icelandic fisheries and implementation of legislation. The fishing season was from early winter (following the annual Icelandic shrimp survey in September/October) until 30 April but in 2017 it was changed to 31 August. TAC and landed catch has followed the advice given by MFRI (Figure 9).

Figure 9: Shrimp in Ísafjarðardjúp. Comparison of the reliased catches, landed catches and the set TAC.

References

Jónsdóttir, I.G. 2024. Handbók um stofnmælingu rækju árið 2024. Kver Hafrannsóknastofnunar, KV2024-007.