Survival of juvenile herring (Clupea harengas membras) after passing through a selection grid in a pontoon trap

Published source details Lundin M., Calamnius L. & Lunneryd S. (2012) Survival of juvenile herring (Clupea harengas membras) after passing through a selection grid in a pontoon trap. Fisheries Research, 127-128, 83-87.
Share Tweet Email

This study is summarised as evidence for the following.

	Action	Category
	Modify fishing trap/pot configuration Action Link

Modify fishing trap/pot configuration

A replicated, controlled study in 2010 in an inshore area of the Bothnian Sea, Sweden (Lundin et al. 2012) found that survival rates of trap-caught small Baltic herring Clupea harengus membras that had passed through a size-sorting escape grid were similar to trap-caught herring that had not passed through a grid. The mortality of herring that had passed through the escape grid was 3–13% compared to 7–45% for herring caught without a grid. When the effects of water temperature variations during the trials were considered, no significant difference in mortality rates between traps was found. Herring were sampled in a herring trap (pontoon trap) in six alternate trials in July-September 2010: three using a stainless steel sorting grid with 14 mm bar spacing and three with no grid. Small herring were caught in the trap by passing through a sorting grid mounted at the entrance of the fish chamber. The trap was then closed and the herring retained in situ for seven days. As control fish, herring of all sizes were trapped without passing through any grid. Numbers of herring enclosed varied between 172 and 2,170. For each trial, herring survival rates after the seven days were assessed.

(Summarised by: Natasha Taylor)