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Professor Arild Folkvord Larval fish ecology, dr. scient. University of Bergen,
1993 |
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Cod larva in Sarsia |
Phone: (+47) 55 58 44 56 |
Cod otolith (lapillus) |
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Fax: (+47) 55 58 44 50 |
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Email: arild.folkvord@bio.uib.no |
Relevant
links:
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Research Recent and
ongoing projects IBACS (Integrated Approach to the
Biological Basis of Age Estimation in Commercially Important Fish Species) TACADAR (Towards Accreditation and
Certification of Age Determination of Aquatic Resources) IBACS (Integrated
approach to Biological basis of Age estimation in Commercially important fish
Species) ANREC
(Association of Physical and Biological processes acting on
Recruitment and post-Recruitment of Anchovy) Meltzer
project (High latitude climate variability and its effect on
human settlement and fishery resources as revealed by fossil otoliths) NFR
project (Optimization of growth performance of juvenile cod
by applying environmental regulation and water quality control) UNCOVER
(Understanding the mechanisms of stock recovery) PRODCOD
(Progressive, modern production of juvenile EUR-OCEANS (European Network of
Excellence for Ocean Ecosystems Analysis) Teaching Master
program i Fiskeribiologi og forvaltning (in Norwegian) Master
program i Marinbiologi – Akvatisk økologi (in Norwegian) Master’s
programme in Fisheries Biology and Management (in English) European
Master’s programme in Aquaculture and Fisheries (In English) Recent PhD’s in Fisheries Biology |
Research profile
The focus of A. Folkvord's research is on growth and survival mechanisms
in the early life of fishes. The research is experimentally oriented, and
covers aspects of marine juvenile production and process oriented recruitment
studies.
Size-selective mortality in cultured fish is often due to aggression and
cannibalism. A large effort has been made to elucidate factors promoting
cannibalism in captive cod (e.g. hunger level, size, size differences etc.).
Size- and temperature dependent growth in juvenile flatfish and cod has also
been studied with the aim of determining the growth potential under culture
conditions. The growth process is very dynamic during the early life stages,
and controlled laboratory experiments are carried out to calibrate methods used
for growth characterization (e.g. RNA:DNA analysis, otolith microstructure
analysis, fatty acid analysis).
The age of field caught fish larvae is often difficult to assess.
Fortunately, growth increments are usually formed on a daily basis in the ear
stones (otoliths) of fish larvae. It is thus possible to estimate the larval
age in days in a similar manner as one determines the age of older fish by
counting yearly zones in the otoliths and scales. The growth pattern in the
otolith also reflects the previous growth history of the larva, and can be used
to determine where, and under what conditions, the larva grew up. The otolith
has therefore often been referred to as the "black box" in fish. An
important part of the ageing research is related to the accuracy and precision
of the age estimation. Knowledge in this field is of great importance in
process studies and fisheries management.
Selected publications
Folkvord A. 2005. Comparison
of size-at-age of larval cod (Gadus morhua L.) from different
populations based on size- and temperature-dependent models. Canadian Journal of Fisheries and Aquatic
Sciences 62: 1037-1052.
Folkvord A, Johannessen A, Moksness E. 2004.
Temperature dependent otolith growth in herring (Clupea harengus)
larvae. Sarsia 89: 297-310.
Skajaa K, Fernö A, Folkvord A. 2003. Swimming,
feeding and predator avoidance in cod larvae (Gadus morhua L.):
trade-offs between hunger and predation risk. In H Browman & AB Skiftesvik
(Editors). The Big Fish Bang: Proceedings of the 26th Annual Larval Fish
Conference. Pp. 105-121.
Folkvord A, Blom G, Johannesen A, Moksness E.
2000. Growth-dependent
age estimation in herring (Clupea harengus L.) larvae. Fisheries
Research 46: 91-103.
Otterlei E, Nyhammer G, Folkvord A, Stefansson S.O. 1999. Temperature
and size dependent growth of larval and juvenile cod (Gadus morhua L.) -
a comparative study between Norwegian coastal cod and
Folkvord A. 1997. Ontogeny of
cannibalism in larval and juvenile fish with special emphasis on cod, Gadus
morhua L. In RC Chambers & ED Trippel (Editors), Early life history
and recruitment in fish populations. Chapman and Hall Ltd.,
Folkvord A, Rukan K,
Johannessen A, Moksness E. 1997. Early life history of herring (Clupea
harengus L.) larvae in contrasting feeding environments determined by
otolith microstructure analysis. Journal of Fish Biology 51(Suppl. A):
250-263.
Folkvord A, Ystanes L,
Johannessen A, Moksness E. 1996. RNA/DNA ratios and growth of herring (Clupea
harengus) larvae reared in mesocosms. Marine Biology 126: 591-602.
Folkvord A, Øiestad V, Kvenseth PG. 1994. Growth-patterns
of three cohorts of
Folkvord A, Blom G, Dragesund O, Johannessen
A, Nakken O, Nævdal G.1994. A conceptual framework for enhancing
and stabilizing recruitment of marine fish stocks. Aquaculture and Fisheries
Management 25(Suppl.1): 245-258.
Folkvord A &
Hunter JR. 1986. Size specific vulnerability of northern anchovy, Engraulis
mordax, larvae to predation by fishes. Fishery Bulletin
Department of Biology - Last update:
January 10, 2006 AF
