@clumpusjim.bsky.social
Fish biologist at Marine and Freshwater Research Institute (Iceland) , wildlife photographer and brewer of beer.
Primarily interested in reproductive ecology of fish and all things lumpfish (C. lumpus).
Primarily interested in reproductive ecology of fish and all things lumpfish (C. lumpus).
With two above average year classes entering the fishery, ICES advice for Norwegian spring-spawning herring increases by 33 % to 533 914 tonnes. doi.org/10.17895/ice...
October 1, 2025 at 10:52 AM
With two above average year classes entering the fishery, ICES advice for Norwegian spring-spawning herring increases by 33 % to 533 914 tonnes. doi.org/10.17895/ice...
After years of coastal states failing to agree to a shared TAC for Atlantic mackerel, leading to catches > advice, ICES advice for 2026 is 71 % lower than in 2025. doi.org/10.17895/ice...
September 30, 2025 at 11:36 AM
After years of coastal states failing to agree to a shared TAC for Atlantic mackerel, leading to catches > advice, ICES advice for 2026 is 71 % lower than in 2025. doi.org/10.17895/ice...
However, a new study shows that early estimates of age at maturity were too high due to biased sampling. Correcting for this results in no significant change in age at maturity over time. 2/n
www.sciencedirect.com/science/arti...
www.sciencedirect.com/science/arti...
July 7, 2025 at 3:05 PM
However, a new study shows that early estimates of age at maturity were too high due to biased sampling. Correcting for this results in no significant change in age at maturity over time. 2/n
www.sciencedirect.com/science/arti...
www.sciencedirect.com/science/arti...
Estimated age at which northeast Arctic and North Sea cod mature has decreased over time. This was considered to be a result of fisheries induced evolution whereby fisheries caught older fish, so fish which matured younger were more likely to spawn. 1/n
July 7, 2025 at 3:05 PM
Estimated age at which northeast Arctic and North Sea cod mature has decreased over time. This was considered to be a result of fisheries induced evolution whereby fisheries caught older fish, so fish which matured younger were more likely to spawn. 1/n
More interesting Greenland shark reproduction tidbits
- Male do not mature until they are at least ~2.6 m
- Females do not mature until they are at least ~3.9 m
- It is estimated that they produce 200–324 pups per pregnancy
- new born pups are 35-45 cm
journals.plos.org/plosone/arti...
- Male do not mature until they are at least ~2.6 m
- Females do not mature until they are at least ~3.9 m
- It is estimated that they produce 200–324 pups per pregnancy
- new born pups are 35-45 cm
journals.plos.org/plosone/arti...
July 4, 2025 at 10:12 AM
More interesting Greenland shark reproduction tidbits
- Male do not mature until they are at least ~2.6 m
- Females do not mature until they are at least ~3.9 m
- It is estimated that they produce 200–324 pups per pregnancy
- new born pups are 35-45 cm
journals.plos.org/plosone/arti...
- Male do not mature until they are at least ~2.6 m
- Females do not mature until they are at least ~3.9 m
- It is estimated that they produce 200–324 pups per pregnancy
- new born pups are 35-45 cm
journals.plos.org/plosone/arti...
2/n Absence of neonates in the evaluated data and the scientific literature in general suggests pupping occurs in bathypelagic or benthic habitats of mid-Atlantic Ridge and/or the Irminger Sea.
July 3, 2025 at 11:17 AM
2/n Absence of neonates in the evaluated data and the scientific literature in general suggests pupping occurs in bathypelagic or benthic habitats of mid-Atlantic Ridge and/or the Irminger Sea.
1/n Fascinating study collating records of Greenland shark across the Atlantic
– males and subadult females found in cold arctic water
– adult females reside in warmer Atlantic water
– large juveniles are common both in high-Arctic and temperate areas
onlinelibrary.wiley.com/doi/10.1002/...
– males and subadult females found in cold arctic water
– adult females reside in warmer Atlantic water
– large juveniles are common both in high-Arctic and temperate areas
onlinelibrary.wiley.com/doi/10.1002/...
July 3, 2025 at 11:17 AM
1/n Fascinating study collating records of Greenland shark across the Atlantic
– males and subadult females found in cold arctic water
– adult females reside in warmer Atlantic water
– large juveniles are common both in high-Arctic and temperate areas
onlinelibrary.wiley.com/doi/10.1002/...
– males and subadult females found in cold arctic water
– adult females reside in warmer Atlantic water
– large juveniles are common both in high-Arctic and temperate areas
onlinelibrary.wiley.com/doi/10.1002/...
What a coincidence, we at @mfri.bsky.social are just coming to the end a three week seabed mapping cruise (blue lines). The data prepared so far is open access and can be downloaded at the MFRI website www.hafogvatn.is/en/research/....
June 21, 2025 at 9:34 PM
What a coincidence, we at @mfri.bsky.social are just coming to the end a three week seabed mapping cruise (blue lines). The data prepared so far is open access and can be downloaded at the MFRI website www.hafogvatn.is/en/research/....
Juveniles and adults were found at different temperatures. Juveniles occurrence peaked at ~6-8°C while adults peaked at ~4-7°C. Occurrence dropped dramatically at temperatures >12°C. (3/n)
May 13, 2025 at 10:32 AM
Juveniles and adults were found at different temperatures. Juveniles occurrence peaked at ~6-8°C while adults peaked at ~4-7°C. Occurrence dropped dramatically at temperatures >12°C. (3/n)
The highest densities of juveniles (<18 cm) are in the central Norwegian Sea (left), whereas highest densities of adults are northeast and northwest of the Norwegian Sea (right).
Red indicates an area where that lifestage was never caught in the history of the survey (2010-2023). (2/n)
Red indicates an area where that lifestage was never caught in the history of the survey (2010-2023). (2/n)
May 13, 2025 at 10:32 AM
The highest densities of juveniles (<18 cm) are in the central Norwegian Sea (left), whereas highest densities of adults are northeast and northwest of the Norwegian Sea (right).
Red indicates an area where that lifestage was never caught in the history of the survey (2010-2023). (2/n)
Red indicates an area where that lifestage was never caught in the history of the survey (2010-2023). (2/n)
When lumpfish are not at the coast spawning (Cyclopterus lumpus), where are they? Turns out, almost everywhere in the Nordic Seas.
New paper documenting the summer distribution of lumpfish doi.org/10.1111/fog..... (1/n)
@mfri.bsky.social
New paper documenting the summer distribution of lumpfish doi.org/10.1111/fog..... (1/n)
@mfri.bsky.social
May 13, 2025 at 10:32 AM
When lumpfish are not at the coast spawning (Cyclopterus lumpus), where are they? Turns out, almost everywhere in the Nordic Seas.
New paper documenting the summer distribution of lumpfish doi.org/10.1111/fog..... (1/n)
@mfri.bsky.social
New paper documenting the summer distribution of lumpfish doi.org/10.1111/fog..... (1/n)
@mfri.bsky.social
A nice catch of Arctic eelpouts, Lycodes reticulatus, north of Iceland.
March 19, 2025 at 11:19 AM
A nice catch of Arctic eelpouts, Lycodes reticulatus, north of Iceland.
At our most northern stations of the survey we caught a few Lycodes seminudus. The Latin name describes it as semi naked because it has scales only on half its body. The common name in both Icelandic and Danish translates as half-naked eelpout, but in English, the longear eelpout.
March 18, 2025 at 4:11 PM
At our most northern stations of the survey we caught a few Lycodes seminudus. The Latin name describes it as semi naked because it has scales only on half its body. The common name in both Icelandic and Danish translates as half-naked eelpout, but in English, the longear eelpout.
115 cm, 16 kg, Northern wolffish (Anarhichas denticulatus) caught north of Iceland. Northern wolffish have very watery flesh to bring their body close to the density of water. This allows them to easily move away from the sea bottom into the pelagic zone.
March 17, 2025 at 1:40 PM
115 cm, 16 kg, Northern wolffish (Anarhichas denticulatus) caught north of Iceland. Northern wolffish have very watery flesh to bring their body close to the density of water. This allows them to easily move away from the sea bottom into the pelagic zone.
Some nice juvenile haddock (Melanogrammus aeglefinus) a common fish here in the north Atlantic and found all around Iceland. So many pictures looked washed out and don´t give credit to how colorful this fish actually is, check out that tail.
March 16, 2025 at 12:35 PM
Some nice juvenile haddock (Melanogrammus aeglefinus) a common fish here in the north Atlantic and found all around Iceland. So many pictures looked washed out and don´t give credit to how colorful this fish actually is, check out that tail.
This will also be the first survey of our brand new vessel Þórunn Þórðardóttir.
March 16, 2025 at 12:18 PM
This will also be the first survey of our brand new vessel Þórunn Þórðardóttir.
The Iceland march groundfish survey, ~500 stations surveyed annually to collect information of the bottom dwelling species down to depths of 500 m. The map can be viewed live at skip.hafro.is. @mfri.bsky.social
March 16, 2025 at 12:18 PM
The Iceland march groundfish survey, ~500 stations surveyed annually to collect information of the bottom dwelling species down to depths of 500 m. The map can be viewed live at skip.hafro.is. @mfri.bsky.social
There was a move towards fewer but bigger boats, which fish for fewer days but haul more nets per trip.
A limit on the number of fishing days in 2005 was implemented to limit catch and improve prices, but this led to an increase in CPUE.
A limit on the number of fishing days in 2005 was implemented to limit catch and improve prices, but this led to an increase in CPUE.
March 3, 2025 at 10:33 AM
There was a move towards fewer but bigger boats, which fish for fewer days but haul more nets per trip.
A limit on the number of fishing days in 2005 was implemented to limit catch and improve prices, but this led to an increase in CPUE.
A limit on the number of fishing days in 2005 was implemented to limit catch and improve prices, but this led to an increase in CPUE.
New paper (doi.org/10.1016/j.rs...) looking at changes in the female lumpfish (Cyclopterus lumpus) gillnet fishery in Iceland in terms of effort in the past 34 years and a look at how to improve the management of this effort based fishery. Published just in time for the switch to a TAC 😉.
March 3, 2025 at 10:33 AM
New paper (doi.org/10.1016/j.rs...) looking at changes in the female lumpfish (Cyclopterus lumpus) gillnet fishery in Iceland in terms of effort in the past 34 years and a look at how to improve the management of this effort based fishery. Published just in time for the switch to a TAC 😉.
Come join us here in Ísafjörður, careful though, after coming here to study, a few never leave.
February 4, 2025 at 11:33 AM
Come join us here in Ísafjörður, careful though, after coming here to study, a few never leave.
New study out from Charlotte Matthews "Biology of One of the Most Abundant Mesopelagic Fish in Icelandic and Surrounding Waters: The Krøyer's Lantern Fish Notoscopelus kroyeri (Malm, 1861)" onlinelibrary.wiley.com/doi/10.1111/... @christophe-p71.bsky.social
January 7, 2025 at 9:10 AM
New study out from Charlotte Matthews "Biology of One of the Most Abundant Mesopelagic Fish in Icelandic and Surrounding Waters: The Krøyer's Lantern Fish Notoscopelus kroyeri (Malm, 1861)" onlinelibrary.wiley.com/doi/10.1111/... @christophe-p71.bsky.social
We have reached day 25 of #25daysoffishmas and we draw to a close with my subject of study, Cyclopterus lumpus, which actually lacks a full common name and is simply called "lumpsucker". This species really stands out from the rest of the family, in terms of appearance, size and behaviour.
December 25, 2024 at 5:02 PM
We have reached day 25 of #25daysoffishmas and we draw to a close with my subject of study, Cyclopterus lumpus, which actually lacks a full common name and is simply called "lumpsucker". This species really stands out from the rest of the family, in terms of appearance, size and behaviour.
On day 24 of #25daysoffishmas we have Brashnikov's lumpsucker, and again, a species with very few specimens. Given the controversies in the lumspucker family, a few more specimens could certainly help tidy things up a bit.
December 24, 2024 at 10:11 PM
On day 24 of #25daysoffishmas we have Brashnikov's lumpsucker, and again, a species with very few specimens. Given the controversies in the lumspucker family, a few more specimens could certainly help tidy things up a bit.
On day 23 of #25daysoffishmas we have Jordan's lumpsucker. Only 3 specimens are known, I am not entirely convinced that this species exists given so few specimens and the morphologically variability inherent in lumpsucker species, but time will tell.
December 23, 2024 at 4:30 PM
On day 23 of #25daysoffishmas we have Jordan's lumpsucker. Only 3 specimens are known, I am not entirely convinced that this species exists given so few specimens and the morphologically variability inherent in lumpsucker species, but time will tell.
On day 22 of #25daysoffishmas we have another species sitting in a monosecific genus, the tentacled lumpsucker. It is nice to find a picture of fresh specimen and not the drab preserved specimens from museum collections.
December 22, 2024 at 1:31 PM
On day 22 of #25daysoffishmas we have another species sitting in a monosecific genus, the tentacled lumpsucker. It is nice to find a picture of fresh specimen and not the drab preserved specimens from museum collections.