Mesopelagic fish
(Chapter 11 NSE)
• Mesopelagic zone by definition 200-1000
m depth
• Some light remains in most of this zone
• Mesopelagic fish are mostly small,
planktivorous fish living in this depth zone
• Adaptations to life at these depths? (see
previous lecture)
Distribution
• Mesopelagic fish abound in the worlds oceans,
apart for high latitudes (Arctic, to some extent
Antarctica)
• Play important, yet often unknown (unquantified)
role in the ecosystem
• One estimate tells that their total abundance is
about 10 times higher than global annual
catches of fish (NB!, even if relatively deepliving; connects with upper, productive layers)
• Fisheries limited due high amount of wax esters
Mesopelagic fishes in the Norwegian Sea
* Maurolicus muelleri
* Benthosema glaciale
* Arctozenus risso
Life history
• Short life span, a few years
• Low fecundity, hundreds to a few thousand
eggs, but matures early
• Larvae in upper layers
Abundance/Trophic position
• Totally about 4 mill tonnes in the Norwegian
Sea?
• Eaten by larger fisk like blue whiting, satihe,
salmon
• Maurolicus muelleri and Benthosema glaciale
forage on plankton (generally not as filter
feeders, which is stated in the book); B. glaciale
takes somwhat larger prey, including krill
• B. glaciale lives deeper than M. muelleri
• Both predators on Calanus spp, likely being
main predators during winter