Key signals
- Landings have been decreasing substantially.
- Stock assessment model (SPiCT) shows that the fishing pressure is currently considerably below FMSY.
General information
The starry ray is by far the most abundant elasmobranch species in Icelandic waters, with a widespread distribution across the Icelandic shelf and upper slope at depths ranging from 20 to 1000 m, though it is most commonly found between 30 and 200 m. In Icelandic surveys, individuals rarely exceed 70 cm in length, with the majority measuring between 30 and 50 cm. Reproduction is thought to occur throughout the year, though it peaks during the summer months.
Fishery
The starry ray is abundant in Icelandic waters and is a common bycatch in a variety of fishing gears. Catches are taken all around Iceland but are concentrated within Faxaflói (Figure 1). The increased landings since the 1990s are partly related to increased retention, partly compensating for lower abundance of the D. batis complex. However, fishing regulations were likely responsible for the high proportion of landings from Danish seine during the 1990s. Between 2007 and 2021, landings were 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 showed a steady decline and have not exceeded 250 tonnes since 2022, mainly due to a drastic decline in longline landings (Figure 2), likely driven by a recent regulation permitting the discarding of starry ray (Regulation 1201/2021). A large proportion of landings is destined for local consumption, linked to the Christmas season. This is reflected in the strong seasonality of landings, with the majority reported between September and 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 1985–2026, with few exceptions, such as the 2022 estimate, which is the highest since 2004 (Figure 5). The biomass index in IS-SMB has decreased from approximately 20000 (average 1985–2000) to 14000 (average 2001-2026). This declining trend is particularly notable for large fish (≥50 cm) during 1993–2008. Since 2010, the index for large fish has remained relatively stable. Estimated biomass of juveniles (≤20 cm) in IS-SMB showed large variation during 2003–2013 but appears stable with an increasing trend over the last decade. In IS-SMH, total biomass is overall lower than in IS-SMB and, in particular, small individuals (≤20 cm) are rarely 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 extent 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 in 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 36-50 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 36 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 over time (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 around 1:1 in the spring survey, but in the autumn survey the ratio is skewed towards females (male:female ratio 1:1.3). Males are on average larger than females (39.5 cm and 37.7 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.
