Key signals
- Landings have been decreasing substantially.
- Stock assessment model (SPiCT) shows that the fishing pressure is currently considerably below FMSY.
General information
Starry ray is by far the most abundant elasmobranch species in Icelandic waters. It has a widespread distribution over the Icelandic shelf and upper slope at depths from 20-1000 m but is most common at 30-200 m. In Icelandic surveys, starry ray is rarely caught larger than 70 cm but most commonly at 30-50 cm. Reproduction is believed to occur to some extent throughout the year, however mainly during summer.
The fishery and landings
Starry ray is abundant in Icelandic waters and is a common bycatch in variety of fishing gears. Catches of starry ray are taken all around Iceland but mostly within Faxaflói in the southwest (Figure 1). The increased landings since the 1990s are partly related to an increased retention, compensating for a lower abundance of the D. batis complex. However, fishing regulations are likely responsible for the high proportion of landings from Danish seine in the nineties. Between 2007- 2021 landings are mainly reported from the longline fishery (Figure 2). Reported landings increased from 500 tonnes in 2007 to more than 1700 tonnes in 2012. Thereafter, landings have shown a steady decline and since 2022 they haven´t exceeded 250 tonnes mainly due to drastic decline in landings from the longline fishery (Figure 2). A large proportion of the landings is for local consumption linked to the yule season. This is reflected in the strong seasonality in landings; most landings are reported from September-November each year (Figure 3).
Survey data
Distribution and biomass indices
Starry ray is a frequent catch in MFRI spring (IS-SMB) and autumn surveys (IS-SMH). Seasonal differences in distributional patterns have been noted, with starry ray much less abundant on the shelf in IS-SMH than in IS-SMB. In IS-SMB, starry ray is found at 86% of all stations, but at about 50% of stations in the IS-SMH (Figure 4).
In general, estimates of total biomass of starry ray in IS-SMB show a declining trend over the survey period 1985-2024 with few exceptions such as the estimate from 2023 which is the highest since 2004 (Figure 5).The biomass index in IS-SMB has decreased from 19 000 (average 1985-2000) to 15 000 (average 2001-2025). Decreasing trend is in particularly notable for large fish (≥50 cm) in years 1993-2008. Since 2010 the index for large fish has remained relative stable. Estimated biomass of juveniles (≤20 cm) in IS-SMB showed large variations in years 2003-2013 but appears to be stable with increasing trend in last decade. In IS-SMH, total biomass are overall lower than in IS-SMB and in particular, small individuals (≤20 cm) are hardly caught.
In MFRI groundfish surveys, starry ray is most abundant in the N and the NW (Figure 6 and Figure 7). In IS-SMB there is a high abundance on the shelf off N-Iceland and in near-shore areas in the south and southeast (Figure 6 a,c,e). In IS-SMH, the main distribution is on the shelf break and starry ray is almost absent from the southern area (Figure 6 b,d,f). Seasonal migration could to some extend explain these seasonal differences in distributional patterns. However, the large seasonal difference in occurrence and catches, especially in the smallest length groups (>30 cm, Figure 6 c,d) could also be partly explained by differences in survey gear (size and weight). Starry ray is a frequent bycatch in several other MFRI surveys.The coastal shrimp survey occurs at various time periods in fjords and near coastal areas and starry ray is widely distributed within the survey areas (Figure 7 a). Similarly, starry ray is a frequent bycatch in the gillnet survey occurring early April each year (Figure 7 b).
In IS-SMB the highest proportion of catch is taken in areas off NW-, NE- and SE- Iceland and the reduction in biomass is most prominent in these areas. In IS-SMH, the highest proportion of catch is taken in areas off NW- and NE-Iceland; the areas where a reduction in abundance has taken place (Figure 8).
Length distributions from surveys indicate that most specimens are <60 cm . Mean size varies from 35-49 cm depending on surveys (Figure 9). The length distribution is negatively skewed as the proportion of large fish decreases quite abruptly (Figure 9) which is likely due to morphological attributes of the species. Mean length in the spring survey is the lowest in all six surveys and considerably lower than mean length in IS-SMH (overall mean 35 and 40 cm, respectively). The proportion of larger fish decreases quite abruptly after reaching 50 cm (Figure 10 and Figure 11). In IS-SMB, the mean length has decreased from 38 cm (average 1996-1998) to 35.8 cm (average 2019-2025) (Figure 10). On the other hand, in IS-SMH the mean length has varied (from 38 cm to 43 cm) over the period without any specific direction (Figure 11).
The sex ratio is 1:1 in the spring survey, but in the autumn survey the ratio is skewed towards females (male:female ratio 1:1.57). Males are on average larger than females (40.5 cm and 38.8 cm, respectively). Data on maturity is sampled in the autumn survey allowing for calculations of maturity ogives. Length-at-50%-maturity (L50) is 43.3 cm and 41.9 cm for males and females, respectively (Figure 12). Anecdotal information suggests that starry ray undertakes seasonal migrations related to egg-laying activity. Recently, both surveys have started to sample data on egg case distribution, but trawl survey data may provide useful information on catches of viable skate egg cases and/or nursery grounds.
