A sea urchin with very high gonad index (GI). (Photo: Nofima)
Nofima creates manual on sea urchin reproductive cycle
Wednesday, April 18, 2012, 22:40 (GMT + 9)
Scientists at Nofima Mat, the Norwegian Institute of Food, Fisheries and Aquaculture Research, have created a manual that provides a thorough introduction to the reproductive cycle of sea urchins. The goal of the project is to provide sea urchin fishers, farmers and researchers with the opportunity to improve the economic gain from sea urchin fishing in Norway.
Sea urchins are primitive animals that lack many of the body parts found in higher animals. They have no specialized respiratory or circulatory systems. No heart, no blood vessels and no oxygen binding molecules in the body fluid and a very simple digestive system.
Basically, they consist of a mouth, intestines, the gonad or roe (which is the reproductive organ as well as the main storage organ) and a primitive nervous system encased in a hard shell, or test.
|The anatomy of the sea urchin Strongylocentrotus droebachiensis. (Image: Vidar Mortensen/Oddvar Dahl, Nofima)
The gonads are the only part of the sea urchin that is valuable and the quantity and quality (and subsequently the value) of the gonads varies considerable throughout the reproductive cycle. Therefore, it is important for both the sea urchin fishing and aquaculture industries to fully understand the animal’s reproductive cycle.
Previous research has shown that food availability, the density of sea urchins and environmental conditions can have a significant impact on the reproductive cycle, the quantity and the quality of the gonads of urchins.
“We have recently studied two sea urchin populations half a km in Kvalsundet, near Tromsø. There we found great variation in the size and in the quality of the gonads, between seasons and populations, even though they lived very close together,” said researcher Philip James.
Such differences will exist between urchin populations along the entire Norwegian coastline and highlight the need to understand the reproductive cycle of sea urchins in order to establish a robust fishery.
The guide is funded by the Fishery and Aquaculture Industry Research Fund (FHF), and will help sea urchin fishermen, farmers and researchers utilize the valuable sea urchin resource in Norway.