| Year | Location(s) | Company | Reference |
|---|---|---|---|
| 2019 | Ísafjarðardjúp, Húnaflói | Þórishólmi ehf. | Guðrún G. Þórarinsdóttir & Steinunn H. Ólafsdóttir 2019, 2020 |
| 2020 | Eyjafjörður/Skagafjörður, Húnaflói (Hrútafjörður, Bitrufjörður, Steingrímsfjörður) | Þórishólmi ehf. | Guðrún G. Þórarinsdóttir et al. 2020a; Steinunn H. Ólafsdóttir et al. 2021 |
| 2020 | Reyðarfjörður, Fáskrúðsfjörður | Emel ehf. | Guðrún G. Þórarinsdóttir et al. 2020b, 2021b |
| 2021 | Jökulfirðir, Seyðisfjörður/Hestfjörður, Álftafjörður | Þórishólmi ehf. | Guðrún G. Þórarinsdóttir et al. 2021b, 2022a, 2022b |
| 2021 | Reyðarfjörður, Fáskrúðsfjörður, Norðfjarðarflói/Mjóifjörður | Þórishólmi ehf. | Guðrún G. Þórarinsdóttir et al. 2021, 2021b, 2021c |
| 2022 | Berufjörður | Emel ehf. | xxx (*) |
| 2022 | Dýrafjörður | Þórishólmi ehf. | xxx (*) |
| 2023 | Reykjarfjörður, Veiðileysufjörður á Ströndum | Þórishólmi ehf. | xxx (*) |
| 2023 | Seyðisfjörður | Emel ehf. | xxx (*) |
| 2023 | Stöðvarfjörður | Emel ehf. | xxx (*) |
| 2023 | Æðey, Kaldalón | Þórishólmi ehf. | xxx (*) |
| 2024 | Bakkafjörður | Emel ehf. | xxx (*) |
| 2024 | Bitrufjörður, Miðfjörður | Þórishólmi ehf. | xxx (*) |
| 2024 | Húnafjörður | Royal Iceland hf. | xxx (*) |
| 2024 | Loðmundarfjörður, Mjóifjörður, Norðfjarðarflói, Reyðarfjörður, Seyðisfjörður | Emel ehf. | xxx (*) |
| 2024 | Steingrímsfjörður, Kollafjörður | Þórishólmi ehf. | xxx (*) |
Key signals
Since 2006 the CPUE index has ranged from 1.08 to 2.23 and has been above Itrigger since 2020.
Fishing pressure proxy is below the target Fproxy. Mean catch length in 2024 is above MSY proxy length (LF=M).
Three new areas have advice i.e. Ísafjarðardjúp, Húnaflói and Austfirðir.
The fishery
Breiðarfjörður
Dredge fishing for the green sea urchin started in 1993. Landings peaked in 1994, at 1500 tonnes but decreased drastically thereafter until 1997 when the fishery stopped. Decreased catches can be attributed to market factors, but the main fishing areas were severely affected by the effort in those years. The fishery was widely distributed around Iceland, but Breiðafjörður was always the main fishing area. In 2004, fishing started again in Breiðafjörður with minimal landings (30–40 tonnes) until 2007 when it reached 134 tonnes. In 2007–2014, landings were 126–146 tonnes but have increased since then. In 2024, approximately 160 tonnes were landed from Breiðafjörður. Standardized CPUE index in Breiðafjörður was 1.92 in 2024 and fluctuated between 1.08 and 2.23 in the years from 2006–2024 (Figure 1). Since 2004, a single vessel has remained active, although in recent years more boats have participated in the fishery. Fishing is conducted from August/September to March/April, partly depending on the quality of the roes.
Húnaflói
Dredge fishing for the green sea urchin in Húnaflói took place during the years between 1993 and 1995 when the fishery was open access, and the landed catch during that period ranged from 50-120 tonnes annually. In Húnaflói, experimental fishing has been conducted since 2019 in the western part of the fjord. In the fishing year 2023/2024, a permit was given to fish in the eastern part of the fjord. In 2024, 48 tonnes were landed from Húnaflói (Figure 3 and Figure 4).
Ísafjarðardjúp
Dredge fishing for the green sea urchin in Ísafjarðardjúp took place during the years 1995, 2017, 2018 and 2019, landings were less than 1 tonne per annum. Experimental fishing for green sea urchins in Ísafjarðardjúp and Jökulfirðir have been conducted since 2021 with landings of 70-85 tonnes per annum (Figure 5). There was also limited fishing in Dýrafjorður in 2022.
Austfirðir
Dredge fishing for the green sea urchin in Austfirðir occurred in 1994 and 2015, primarily in Berufjörður, with catches ranging from 0.3 to 41 tonnes. Since 2020, experimental fishing permits have been issued annually for various locations in Austfirðir. Most of this fishing has taken place in Reyðarfjörður (area C), followed by Norðfjarðarflói (area B) and Seyðisfjörður (area A) (Figure 7), with lower catches—typically under 10 tonnes—in other fjords (Fáskrúðsfjörður, Berufjörður, Seyðisfjörður and Stöðvafjörður) (Figure 8). The total catch across all of East Iceland from 2020 to 2024 ranged between 25 and 60 tonnes.
Experimental fishing
Since 2019, experimental fishing licenses for green sea urchin have been granted to explore fishable stocks across various fjords and coastal areas in Iceland. Initial efforts focused on Ísafjarðardjúp and Húnaflói, followed by investigations in Eyjafjörður, Skagafjörður, Jökulfirðir, Seyðisfjörður, Álftafjörður, and several locations in the East Fjords (including Reyðarfjörður, Fáskrúðsfjörður, and Norðfjarðarflói/Mjóifjörður (see Table 1).
Sea urchin survey in Breiðafjörður
Surveys were conducted in September 2015, April 2016 and September 2018 to assess biomass of sea urchin in the main fishing area in southern Breiðafjörður south of 65°10’N and east of 22°40’W at depths of 8–60 m, by swept area method and underwater photography. Most of the tows (88%) were at depths of 8–35 m. The surveys were conducted by a commercial sea urchin fishing vessel (Fjóla SH-7). The dredge used is 250 cm in width and with a 150 cm long catch–bag. The mesh size of the catch–bag is 100 mm.
To determine the density/abundance of urchins, each catch was weighed, and the distance covered by the dredge was calculated. The total catch weight was divided by the size of the area covered in each tow to give biomass in kg/m²:
\[ \text{Swept Area} = \text{Dredge Width} \times \text{Distance Towed} \]
\[ \text{Biomass (kg/m²)} = \frac{\text{Catch Weight (kg)}}{\text{Swept Area (m²)}} \]
Biomass estimates for any given area were calculated from the mean biomass in that area multiplied by the total size of the area:
\[ \text{Stock Biomass (kg)} = \text{Mean Biomass (kg/m²)} \times \text{Total Area (m²)} \]
The density (individuals per m²) was calculated by dividing the biomass by the mean wet weight of individual sea urchins:
\[ \text{Density (individuals/m²)} = \frac{\text{Biomass (kg/m²)}}{\text{Mean Individual Wet Weight (kg)}} \]
An underwater camera was used to estimate the density of urchins in April 2016. Photographs were taken at 19 sites within four of the seven investigated subareas. At each site, photographs were taken at several locations, with a total of 160 photos taken. Later, sea urchins from the photos were counted and the density observed (individuals/m²).
The results from the dredge survey from the same area at the same time were compared to the density observed from the photos before dredging to assess the efficiency of the dredge. The results showed a patchy distribution of the green sea urchin in Breiðafjörður, showing smaller fishing areas, ranging in size from 0.3–3.4 km².
The mean combined abundance in all areas investigated in September 2015 and April 2016 (91 stations) was 0.28 kg/m². The stock size for the study area was assessed to be about 2700 tonnes. The average efficiency of the dredge was estimated at 29% (Þórarinsdóttir and Guðlaugsdóttir 2018).
A survey was conducted on 3–4 September 2018 to estimate the biomass of sea urchin in the main fishing area in Breiðafjörður. Data was collected and handled in the same way as in the years before. In this survey, 40 stations were investigated, and 15 samples were taken from the catch to estimate the size and weight of sea urchins as well as the number and weight of species in the bycatch. The results indicated abundance of 0.24 kg/m² when corrected for average dredge efficiency. The stock size was assessed to be about 2300 tonnes in the area investigated.
An underwater camera survey was conducted on 24 August 2018. Photographs were taken in 30 different sites at 10 stations within each site with approximately 8 repetitions in each station. Processing of this data is still underway.
To investigate the reproductive cycle (gametogenesis and spawning), 30 samples were collected monthly from September 2016–August 2017 (except June and July), from two different fishing areas at 60 and 32 m depth, respectively. A total of 300 urchins were collected at each site. For each sample, test diameter for each urchin was measured to the nearest 0.1 mm with Vernier calipers and the total weight to the nearest 0.1 mg. The urchins were opened and drained and weighed again and the water content in each individual estimated. The gonads were removed, blotted dry, their wet weights determined, and the gonadosomatic index (GI) was calculated as:
\[ \text{Gonadosomatic Index (\%)} = \frac{\text{Gonad Weight (g)}}{\text{Total Body Weight (g)}} \times 100 \]
Length distribution of green sea urchins
The size distribution of sea urchins in the surveyed area was analyzed for the combined years of 2015 and 2016. The results revealed that the majority of the sea urchin population during this period fell within the 56–60 mm test diameter range. Overall, the diameters of individuals ranged from 17 mm to 85 mm, indicating a relatively broad distribution of sizes within the population. The mean test diameter across all fishing areas sampled in 2015 and 2016 was calculated to be 59.3 ± 10.5 mm, reflecting a predominance of individuals above the minimum legal landing size of 45 mm (Figure 9). In September 2018, a subsequent survey was carried out to assess the current status of the stock. This survey showed a shift in size distribution. The mean test diameter observed in 2018 had decreased to 50.0 ± 13 mm, suggesting a possible change in population structure or recruitment patterns compared to the earlier survey (Figure 10). The most frequent size class in 2018 was slightly broader, with the highest proportion of individuals falling within the 55–64 mm range. The total size distribution observed during this survey extended from as small as 5 mm up to 79 mm in diameter, indicating the presence of both juvenile and adult individuals in the population.
It is important to note that, according to Icelandic fisheries regulations, sea urchins with a diameter smaller than 45 mm are not permitted to be landed for commercial purposes. This regulation is intended to protect juvenile individuals and ensure the sustainability of the stock by allowing them to reach maturity and contribute to reproduction before being harvested. The minimum legal landing size is specified in Regulation No. 765/2020.
Reproductive cycle of sea urchin
The green sea urchin exhibits a well-defined annual reproductive cycle, as evidenced by seasonal fluctuations in the gonad index (GI) over the course of a year. To investigate this pattern, a year-long study was conducted from September 2016 to August 2017 in Breiðafjörður, at two depths: 32 meters (65°06’N, 22°32’W) and 60 meters (65°05’N, 22°33’W). The results revealed consistently high gonad index values at both depths throughout the study period, indicating sustained gonad development. However, the gonad index was consistently lower at the deeper (60 m) site compared to the shallower (32 m) site. A distinct spawning event was observed at both depths in April, marking the primary spawning season. At 32 meters, minor spawning activity continued into May, suggesting a slightly extended reproductive period in shallower waters (Figure 11).
Gonad quality was assessed visually by comparing the color of roe samples to a standardized Pantone color chart specifically developed for sea urchin research (Ásbjörnsson, 2011). Photographs of each gonad sample were taken in the laboratory, and the color of each was matched to the corresponding shade on the chart. Based on these comparisons, each sample was assigned a quality rank. The proportion of samples falling into each rank category was calculated monthly for both depths (Figure 12). The quality ranks were further grouped into four categories based on their market value, providing a practical classification framework for assessing commercial suitability.
- 1st class - Yellow, Light Yellow, Orange, Light Orange
- 2nd class - Dark Yellow, Dark Orange
- 2nd/3rd class - Light Red, Red, Curry Yellow, Curry, Curry Brown
- Unacceptable - Dark Red, Light Brown, Brown, Dark Brown, Curry Grey
At both sampling depths, the majority of sea urchin gonads were classified within acceptable quality ranks—specifically 1st, 2nd, and 2nd/3rd class—while the proportion of unacceptable color grades remained very low throughout the year (Figure 12). Over the course of the study, 94.5% of gonad samples from 32 meters and 91.5% from 60 meters were deemed acceptable in color quality. The highest incidence of unacceptable gonad coloration was observed during the post-spawning period in May at both depths, with an additional peak in April at the 60-meter site. Overall, the shallower site (32 m) consistently yielded a higher proportion of 1st-class roe and a lower proportion of roe deemed unacceptable compared to the deeper site (60 m), with only minor deviations from this trend (O’Hara, 2019).
Other species
Two large species of sea urchins are found around Iceland: the green sea urchin (Strongylocentrotus droebachiensis) and the European edible sea urchin (Echinus esculentus), both of which are utilized for human consumption. Although both species can be found in Icelandic waters, the market clearly prefers the green sea urchin, and no documented fishery or landings currently exist for the European edible sea urchin in Iceland.
However, some caution is warranted when interpreting landings from Breiðafjörður, as there is a possibility that European edible sea urchins have occasionally been misidentified and landed as green sea urchins. The two species are visually similar, particularly because the European edible sea urchin has a violet coloration (Figure 13, left), a color that also appears within the green sea urchin population (Figure 13, right), despite its more typical green to brownish hues.
A key distinguishing feature between the two is their size. The green sea urchin typically reaches a maximum test diameter of 8–10 cm, while the European edible sea urchin can grow significantly larger, up to 16 cm.
Stock assessment
The assessment is based on the rfb-rule for ICES category 3 data-limited stocks and is applied for green sea urchin for the next two fishing years i.e. 2025/2026 and 2026/2027, as it is a biennial advice.
Diagnistics on generalized linear model
The stock assessment is based on trends in biomass indicators and catches, using catch data and catch per unit effort (CPUE) as input. However, raw CPUE values may not accurately reflect stock abundance or changes in stock size, as they do not account for variations in fishing effort—such as differences in the number of vessels operating, or variations in spatial and temporal fishing patterns. To address this, CPUE data were standardized using a Generalized Linear Model (GLM), incorporating factors such as month and vessel identity. An analysis of deviance table is presented below to show the contribution and significance of each factor included in the model (Table 2).
| Term | Df | Deviance | Resid_Df | Resid_Dev | F_value | Pr_F |
|---|---|---|---|---|---|---|
| NULL | NA | NA | 4068 | 1721.19 | NA | NA |
| factor(year) | 19 | 326.79 | 4049 | 1394.40 | 70.106 | < 2.2e-16 *** |
| factor(month) | 9 | 139.82 | 4040 | 1254.58 | 63.324 | < 2.2e-16 *** |
| factor(vessel_nr) | 4 | 264.39 | 4036 | 990.18 | 269.418 | < 2.2e-16 *** |
Application of the rfb-rule
• r is calculated as the average of last two years values, divided by average of three preceding years values which results in r=0.999 (Figure 15).
• b is the biomass safeguard and is used to reduce catch advice when index falls below trigger. The lowest index or the Iloss for sea urchin is 1.08 and was recorded in the year 2019. Itrigger is Iloss *1.4 or 1.51 (Figure 15). Biomass index this year is 1.92 and above Itrigger and b is therefore 1.
• f is the length-ratio component. The mean length of last year’s catch was 6.44 cm and the target reference length LF=M (Lc (5.2 cm), the length where frequency is half that of the modal value * 0.75 + L∞ * 0.25) is 6.025 (Figure 16).
• m is the tuning parameter and for slow growing species (with von Bertanlaffy K<0.2). Green sea urchin is a slow growing species (Blicher et al. 2007) and thus, m=0.95.
Management
The green sea urchin fishery in Breiðafjörður is managed following the advice provided by the ICES rfb-rule for Category 3 data-limited stocks, as detailed in the stock assessment section. The biennial catch advice is based on the standardized CPUE index reflecting stock trends, along with precautionary biomass safeguards. The initial advice for green sea urchins in new areas is based on results from experimental fishing in each area and applies for the next three fishing years.
- presents the annual TAC recommendations, total reported landings, and both standardized and raw CPUE values. (Table 4) provides a spatial breakdown of landings by fishing area, which is relevant for regional management considerations within the fishing grounds.
| Year/Fishing year | Advice | Landings | CPUE index | CPUE |
|---|---|---|---|---|
| 2010/2011 | 138 | 1.47 | 400.6 | |
| 2011/2012 | 152 | 1.39 | 381.9 | |
| 2012/2013 | 127 | 1.27 | 364.6 | |
| 2013/2014 | 148 | 1.42 | 402.2 | |
| 2014/2015 | 256 | 1.5 | 438.7 | |
| 2015/2016 | 293 | 1.38 | 339.9 | |
| 2016/2017 | 250 | 313 | 1.66 | 359.1 |
| 2017/2018 | 250 | 376 | 1.45 | 349.5 |
| 2018/2019 | 250 | 411 | 1.28 | 339.4 |
| 2019/2020 | 275 | 281 | 1.08 | 349.3 |
| 2020/2021 | 220 | 222 | 1.72 | 350.5 |
| 2021/2022 | 196 | 198 | 1.46 | 386.1 |
| 2022/2023 | 188 | 188 | 2.23 | 336.4 |
| 2023/2024 | 194 | 197 | 1.68 | 306.8 |
| 2024/2025 | 194 | 167 | 1.92 | 467.5 |
| 2025/2026 | 197 | |||
| 2026/2027 | 197 |
| Year | Landings north | Landings south | Landings in A | Landings in B | Landings in C | Landings east A | Landings east B | Landings east C | Landings east other | Landings Ísafjörður other | Landings Ísafjarðardjúp | Húnaflói | Total catch |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2019 | 27 | 120 | - | - | - | - | - | - | 0 | - | - | 50 | 197 |
| 2020 | - | - | 36 | 55 | 30 | - | - | 25 | 1 | - | - | 85 | 232 |
| 2021 | - | - | 34 | 90 | 69 | - | 6 | 39 | 0 | - | 85 | 27 | 352 |
| 2022 | - | - | 55 | 82 | 63 | - | 19 | 13 | 4 | 11 | 69 | 23 | 339 |
| 2023 | - | - | 69 | 111 | 64 | 8 | 34 | 10 | 8 | - | 80 | 69 | 453 |
| 2024 | - | - | 28 | 70 | 44 | 12 | 28 | 20 | 0 | - | 80 | 48 | 330 |
References
Ásbjörnsson, H.P. (2011). Management and Utilization of Green Sea Urchin (Strongylocentrotus droebachiensis) in Eyjafjörður, Northern Iceland. Unpublished master’s thesis. University of Akureyri, School of Business and Science, Akureyri, Iceland.
Blicher, M. E., Rysgaard, S., & Sejr, M. K. (2007). Growth and production of sea urchin Strongylocentrotus droebachiensis in a highArctic fjord, and growth along a climatic gradient (64 to 77 N). Marine Ecology Progress Series, 341, 89-102.
Guðrún G. Þórarinsdóttir and Steinunn H. Ólafsdóttir. (2019). Könnun á útbreiðslu skollakopps (Strongylocentrodus droebachiensis) í Ísafjarðardjúpi. Haf- og vatnarannsóknir HV 2019-60.
Guðrún G. Þórarinsdóttir and Steinunn H. Ólafsdóttir. (2020). Könnun á útbreiðslu skollakopps (Strongylocentrodus droebachiensis) í Húnaflóa. Haf- og vatnarannsóknir HV 2020-04. Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2020a). Könnun á útbreiðslu skollakopps (Strongylocentrotus droebachiensis) í Eyjafirði og Skagafirði. Haf- og vatnarannsóknir HV 2020-12.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2020b). Könnun á útbreiðslu skollakopps Strongylocentrotus droebachiensis í Reyðarfirði. Haf- og vatnarannsóknir HV 2020-15.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2021). Könnun á útbreiðslu skollakopps Strongylocentrotus droebachiensis í Reyðarfirði 2021. Haf- og vatnarannsóknir HV 2021-28.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir & Jónas P. Jónasson. (2021b). Könnun á útbreiðslu skollakopps Strongylocentrotus droebachiensis í Fáskrúðsfirði 2021. HV 2021-43.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2021b). Könnun á útbreiðslu skollakopps (Strongylocentrotus droebachiensis) í Jökulfjörðum. Haf- og vatnarannsóknir, HV 2021-61.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2021c). Könnun á útbreiðslu skollakopps (Strongylocentrotus droebachiensis) í Norðfjarðarflóa og Mjóafirði. Haf- og vatnarannsóknir, HV 2021-48.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2021d). Könnun á útbreiðslu skollakopps (Strongylocentrotus droebachiensis) í Jökulfjörðum. Haf- og vatnarannsóknir, HV 2021-61.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2022). Könnun á útbreiðslu skollakopps (Strongylocentrotus droebachiensis) í Seyðis- og Hestfirði. Haf- og vatnarannsóknir, HV 2022-01.
Guðrún G. Þórarinsdóttir, Steinunn H. Ólafsdóttir og Jónas P. Jónasson. (2022). Könnun á útbreiðslu skollakopps (Strongylocentrotus droebachiensis) í Álftafirði. Haf- og vatnarannsóknir, HV 2022-07.
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ICES (2023): Eleventh Workshop on the Development of Quantitative Assessment Methodologies based on LIFE-history traits, exploitation characteristics, and other relevant parameters for data-limited stocks (WKLIFE XI). ICES Scientific Reports. Report. https://doi.org/10.17895/ices.pub.22140260.v1
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Comments on the assessment and the advice
The assessment is based on ICES \(rfb\)-rule for data limited stocks and was applied for the first time in 2021, where life history traits, exploitation characteristics and other relevant parameters for data-limited stocks are considered (ICES 2021). The \(rfb\)-rule has the following form:
\[ A_{y+1} = A_{y-1} \ {r}\ {f} \ {b} \ {m} \]
where \(A_{y+1}\) is the advised catch, \(A_{y-1}\) is last years advice, \(r\) corresponds to the trend in biomass index (as in the current ICES “2 over 3” rule), \(f\) is a proxy for the exploitation (mean catch length divided by an MSY reference length) and \(b\) a biomass safeguard (reducing the catch when biomass index drops below a trigger value). The advice is biennial and thus applies for the next two fishing years (ICES 2023).
\(r\) is the ratio of the mean of the last two survey indices and the mean of the three preceding values or:
\[ \begin{align} r = \frac{ \sum_{i=y-2}^{y-1}I_1/2 }{ \sum_{i=y-3}^{y-5}I_1/3} \end{align} \]
\(f\) is the length-ratio component where
\[ f = \frac{ \overline{L}_{y-1} } {L_{F=M}} \]
where \(\overline{L}\) is is the mean catch length above \(L_{F=M}\). \(L_{F=M}\) is calculated as:
\[ L_{F=M} = 0.75L_c + 0.25L_\infty \] where \(L_c\) is length at first capture and \(L\infty\) is maximum length from catches \(L\infty\).
\(b\) is the biomass safeguard and is used to reduce catch advice when index falls below trigger \[ b=min(1, I{_y-1}/I_{trigger}) \] where \(I_{trigger}\) = \(i_{loss\omega}\)
\(m\) is a multiplier based on stock growth. For slow growing species, \(m\) = 0.95 but for fast growing species, \(m\) is 0.95.