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,
• 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