The primary scientific goal of the Northeast Regional Cod
Tagging Program was to tag and release 100,000 Atlantic cod
throughout the Gulf of Maine and neighbouring Canadian and
New England waters, with the aim of improving our understanding
of cod movements in the region.
The first part of this goal has been achieved! Through the
hard work of over 250 fishermen working with ~25 scientists,
we have exceeded our milestone by tagging >114,000 cod.
However, the ultimate ability of this Program to provide reliable
information on the movement patterns of cod is solely dependant
on the continued support of the region’s fishermen by
continuing to report recaptures of these tagged fish.
Tag returns from this Program, though low, have risen steadily
over the months. These returns are already providing us with
valuable information, but the more returns that are reported,
the more accurate future analysis and conclusions will be.
At present, there is considerable variation in the number
of tags reported from each region and this variation does
not necessarily reflect cod abundance or fishing effort for
these areas. As such, the current data could mis-represent
the movement which is actually occurring. For example, the
number of tags released by our Canadian partners for this
Program is ~5,600, which is ~5.6% of the total tag releases.
However, Canadian fishermen and processors have reported ~15%
of the total number of tag returns and their information shows
a strong movement of cod from Georges Bank into the Bay of
Fundy and other Maritime waters. In contrast, fewer tag returns
to date show a southerly movement into American waters. While
this data could reflect the true primary direction of movement,
it may also be an artefact of greater willingness of Canadians
to report tags (and/or less willingness of Americans to report
tags). It is important for fishermen who are sceptical about
this Program and how its data will be used, to understand
that skewed data will only compromise the accuracy of the
final result, which in the long run, will not best serve the
fishery.
This data is not intended to estimate stock abundance, but it
will provide valuable information on how the cod stocks move,
mix and grow.
The higher the number of tags reported, the more representative
and accurate, the data.
Certain biological data collected through this Program (e.g.
growth information) can supplement the data used in current
cod biological assessments, and should help verify or improve
the accuracy of these calculations.
Skewed data, due to reluctance to return tags from different
fishing regions and gear types, could jeopardize the integrity
of the data obtained, and could lead to mis-representative conclusions.
Around 250 fishermen have worked on this highly collaborative
Program, and it would be rewarding for them to see good results
and science come out of their efforts.
Many fishermen have expressed an interest in seeing more advanced
tagging techniques (e.g. acoustic and data storage tags) being
used. However, unless we begin to see an increase in tag-return
rate, it would be difficult to justify funding such a study,
since these techniques are more expensive and often require
the fish to be recovered for data-download. If tagged fish are
not returned, this data is lost.
We
thank those of you who have diligently returned tags for the
duration of this Program - your input has been greatly appreciated.
We hope that you will continue to report recapture information,
and please also encourage your colleagues to do so. We look
forward to receiving tagged cod returns during 2006 and beyond.
Last
updated January 25th 2005
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