GREATER SILVER SMELT

Key signals

• Survey biomass has been increasing since 2013 and reached the highest levels in the timeseries in 2023.

• Recruitment was higher 10 years ago, which explains the increase in survey biomass, but is around average this year.

• Length distributions are very consistent from one year to another as measured in the autumn survey, with a mean length of ~39 cm.

• Spawning stock biomass has been increasing since 2013 and is at an all time high, but has been above \(B_{lim}\) since 2014.

• Fishing mortality (F) is below \(F_{MSY}\) and has been since 2017.

General information

Greater silver smelt is a rather small silvery bathypelagic species that can form large schools close to the seafloor mainly at depths >500 m. In Icelandic waters it can live to around 26 years old. Juveniles tend to aggregate in shallower depths. Greater silver smelt mainly feed on zooplankton (e.g., euphausiids, amphipods, and copepods) or small nekton (e.g., squids, jellyfish, or fish).

The Fishery

Landings trends

Landings of greater silver smelt are presented in Table 1 and Figure 1. Since directed fishery started in 1997–1998, the landings increased from 800 t in 1996 to 15 200 t in 1998. Between 1999 and 2007 catches varied between 2700 to 6700 t. Since 2008 landings have increased substantially, from 4200 t in 2007 to almost 16 400 t in 2010. In 2011 landings started to decrease due to increased management actions. Since 2019, landings have increased and amounted to 9032 in 2024. Landings were reported in Greenlandic waters in 2017 and 2018; however, these exploratory directed fisheries appear to have ceased in 2019 but should be monitored for re­appearance.

Figure 1: Greater silver smelt. Nominal landings from Icelandic waters.

Greater silver smelt is mostly fished along the south and southwest coast of Iceland, at depths between 500 and 800 m, as targeted fishing is only allowed at depths greater than 400 m (Figure 2). Greater silver smelt has been caught in bottom trawls for years as a bycatch in the redfish fishery. Only small amounts were reported prior to 1997 as most of the greater silver smelt was discarded.

Figure 2: Greater silver smelt. Depth distribution of catches from Icelandic logbooks. All gears combined.

Fleets

Since 1996 between 20 and 40 trawlers have annually reported catches of greater silver smelt in Icelandic waters (Table 1). The trawlers participating in the greater silver smelt fishery also target Icelandic slope beaked redfish (Sebastes mentella) and to lesser extent Greenland halibut and blue ling. Number of hauls peaked in 2010, but have decreased since then in line with lower total catches. In the most recent years number of hauls have increased. In most years over 50% of the greater silver smelt catches are taken in hauls where the species is more than 50% of the catch (Table 1).

Table 1: Greater silver smelt in Icelandic waters. Information on the fleet reporting catches of greater silver smelt.

Year	Number of trawlers	Number of hauls	Reported catch (tonnes)	No. hauls which GSS > 50% of catch	Proportion of catch in hauls where GSS > 50%
1997	26	874	2282	355	0.822
1998	40	2683	11389	1991	0.947
1999	25	1509	4564	810	0.849
2000	23	1301	3550	608	0.797
2001	26	794	1606	245	0.692
2002	32	1160	3158	468	0.744
2003	30	1176	2005	213	0.473
2004	27	1052	2733	292	0.653
2005	30	1388	3558	335	0.707
2006	31	1554	3736	355	0.690
2007	27	1275	3470	416	0.718
2008	31	3261	8569	848	0.648
2009	34	3555	10425	1010	0.680
2010	36	4847	16500	1821	0.727
2011	34	3309	10237	961	0.715
2012	31	3395	9776	988	0.710
2013	31	2743	7247	609	0.642
2014	24	2363	6195	487	0.608
2015	24	2195	5835	356	0.574
2016	26	2096	5719	385	0.593
2017	21	1363	3894	236	0.584
2018	20	1440	3893	215	0.479
2019	28	1169	2570	143	0.506
2020	25	1170	2968	174	0.475
2021	27	1166	3439	189	0.663
2022	31	1697	6230	468	0.726
2023	25	1992	5321	348	0.652
2024	29	1966	8333	591	0.858

Targeting and mixed fisheries issues in the fishery in Icelandic waters

Mixed fisheries issues: species composition in the fishery

Redfish spp. (golden redfish (Sebastes norvegicus) and deepwater redfish (S. mentella)) are the main bycatch species in the mixed fishery encompassing greater silver smelt. Other species of lesser importance are Greenland halibut, blue ling and ling. Other species than these rarely exceed 10% of the bycatch in the greater silver smelt fishery in Icelandic waters (Table 2).

Table 2: Greater silver smelt in Icelandic waters. Proportional (%) bycatch species composition where greater silver smelt was more than 50% of the total catch in a haul.

Year	Golden redfish	Deepwater redfish	Greenland halibut	Ling	Blue ling	Other
1997	1.4	79.3	0.0	6.8	7	5.4
1998	5.2	77.5	0.0	3.5	7	6.7
1999	4.1	79.8	0.0	2.7	6	7.6
2000	4.9	70.9	0.2	0.3	10	13.7
2001	22.7	55.0	4.5	0.5	1	16.1
2002	17.3	73.9	0.4	1.2	4	3.1
2003	38.4	51.2	0.4	0.0	5	4.8
2004	24.9	68.7	0.7	0.1	1	4.8
2005	15.4	69.9	4.2	1.4	3	6.1
2006	28.8	59.8	1.4	0.9	1	8.1
2007	11.9	71.2	5.9	0.3	6	4.6
2008	26.7	60.8	2.8	1.2	5	3.3
2009	20.1	64.6	3.2	0.2	8	4.0
2010	16.0	63.7	2.0	0.9	6	11.1
2011	13.2	66.4	2.2	0.4	5	13.0
2012	8.8	67.3	1.3	0.2	8	14.8
2013	9.5	63.9	4.6	0.1	9	12.6
2014	2.5	78.3	2.8	0.3	5	10.7
2015	12.6	64.1	4.7	0.2	4	14.5
2016	10.9	73.5	5.4	0.2	3	7.1
2017	2.9	85.6	1.6	0.2	3	6.8
2018	4.7	87.7	2.0	0.0	2	4.0
2019	7.8	81.2	1.8	0.6	2	7.0
2020	5.6	87.5	1.7	0.1	1	4.2
2021	11.6	72.3	5.8	0.3	1	8.7
2022	5.7	84.0	4.0	0.2	3	2.9
2023	10.6	58.9	21.4	0.3	2	6.8
2024	9.8	64.4	5.0	0.6	4	16.3

Spatial distribution of catches through time

Most of the catches since 1997 have been taken at the southern edge of the Icelandic shelf (Figure 3). In the period, a gradual relative increase is seen in the western area and a gradual decrease in the southeastern area (Figure 3).

Spatial distribution of catches in Icelandic waters has not changed markedly in recent years (Figure 3 and Figure 4) but fishing for greater silver smelt in the NW area seems to have reduced (Figure 3).

Figure 3: Greater silver smelt. Catch distribution and proportions by area according to logbooks.

Figure 4: Greater silver smelt. Spatial distribution of catches as reported in logbooks.

Table 3: Greater silver smelt. Landings (tonnes) records from the Icelandic directorate of Fisheries and Greenland.

Year	Section 5.a	Section 14.b	Total
1988	241	0	241
1989	8	0	8
1990	113	0	113
1991	246	0	246
1992	657	0	657
1993	1526	0	1526
1994	756	0	756
1995	586	0	586
1996	881	0	881
1997	3935	0	3935
1998	15242	0	15242
1999	6681	0	6681
2000	5657	0	5657
2001	3043	0	3043
2002	4960	0	4960
2003	2680	0	2680
2004	3645	0	3645
2005	4482	0	4482
2006	4769	0	4769
2007	4227	0	4227
2008	8778	0	8778
2009	10828	0	10828
2010	16428	0	16428
2011	10516	0	10516
2012	9289	0	9289
2013	7155	0	7155
2014	6344	4	6348
2015	6058	23	6081
2016	5646	16	5662
2017	4344	666	5010
2018	4035	425	4460
2019	3209	2	3211
2020	3775	27	3802
2021	4140	15	4155
2022	6886	28	6914
2023	5268	0	5268
2024	9032	0	9032

Data available

In general, sampling from commercial catches is considered representative of the stock, as one of the requirements of owning a fishing license for greater silver smelt is the retention of scientific samples (Table 4). Samples were only obtained from bottom trawls. The sampling does seem to cover the spatial and temporal distribution of catches. In recent years there was a decline in sampling which has been improved since 2023. The sampling coverage in 2025 is shown in Figure 5.

Figure 5: Greater silver smelt. Fishing grounds as reported in logbooks and positions of samples taken from landings (asterisks).

Landings and discards

Landings by Icelandic vessels are given by the Icelandic Directorate of Fisheries. Discarding is banned in Icelandic waters, and currently there is no available information on greater silver smelt discards. It is however likely that unknown quantities of greater silver smelt were discarded prior to 1996.

Length compositions

Table 4 gives the number of samples and measurements available for calculations of catch in numbers of greater silver smelt in Icelandic waters. Mean length of greater silver smelt in catches has been rather stable from 2005 in the range of 37 – 43 cm (Figure 6). However, there was a slight increase in mean length in 2012 and again in 2018 (Figure 6).

Figure 6: Greater silver smelt. Relative length distributions from Icelandic commercial bottom trawl catches.

Age compositions

Table 4 gives the number of samples and measurements available for calculations of catch in numbers of greater silver smelt in Icelandic waters. Mean ages from catches have been variable from 2000 in the range 6 – 14 years, with relatively high mean ages when catches are low (Figure 7, Figure 8, Figure 9). The reason for these changes is not known as there is no marked difference in the spatial distribution of the fishery; however, reduced fishing pressure may be a factor.

Table 4: Greater silver smelt. Summary of sampling intensity and overview of available data.

Year	No. length samples	No. length measurements	No. otolith samples	No. aged otoliths
1997	48	4992	1447	1059
1998	148	15559	6964	889
1999	58	4163	2180	82
2000	27	2968	1011	113
2001	10	489	245	17
2002	21	2270	360	127
2003	63	5095	425	0
2004	34	997	225	84
2005	49	3708	772	0
2006	29	4186	616	525
2007	14	2158	285	272
2008	44	3726	1768	1387
2009	53	5702	1746	1574
2010	134	16353	3370	3120
2011	63	6866	1953	1774
2012	43	4440	1492	603
2013	47	4977	710	704
2014	39	4709	350	340
2015	11	1275	221	217
2016	45	5879	285	283
2017	29	3466	430	416
2018	12	1437	185	181
2019	10	1250	40	40
2020	12	1905	130	130
2021	14	1301	215	214
2022	8	603	165	165
2023	28	2789	479	476
2024	23	1964	455	448

Figure 7: Greater silver smelt. Catch weights by age from the commercial fishery in Icelandic waters.