Evaluating Handling/Tagging Effects, In-River Residence Time and … · Evaluating Handling/Tagging...

Evaluating Handling/Tagging Effects, In-River Residence Time and Post-Spawn Migration

of Anadromous River Herring in the Hudson River, New YorkWes Eakin, Cornell University in cooperation with the New York State Department of Environmental Conservation’s Hudson River Fisheries Unit, New Paltz, NY

Figure 4. Coastal tag returns traversing over approximately 500 miles for

male blueback (Tag ID 8085).

Results

• 23 of 25 tagged fish were detected post release

• Alewives = 0% tagging mortality

• Bluebacks = 17% tagging mortality

• 6 of remaining 23 tagged fish “disappeared” during study

(Figure 2)

• “Disappeared” in areas of heavy harvest from recreational

and commercial fisheries

Acknowledgments

I would like to thank Dewayne Fox, Keith Dunton, the Massachusetts Division of

Marine Fisheries and the Maine Department of Marine Resources for sharing

transmitter detections. I thank the New England Interstate Water Pollution Control

Commission, New York State Department of Environmental Conservation and the

Hudson River Estuary Program for their support during this project.

5/7/2013

5/21/2013

Costal Movement of Blueback Male Tag ID 8085

6/8/2013

7/5/2013

Figure 1. Gastric insertion of acoustic tag.

Conclusions

• This study illustrates the importance of:

• Selecting the appropriate location and timing of tagging

events

• The Atlantic Coastal Telemetry (ACT) Network and its ability

to connect researchers to data that would otherwise be

unavailable

• Recommendations for future studies:

• Upstream migrating anadromous fishes should be tagged

early in their migration and before they reach their spawning

grounds and when possible utilizing multi-year tags

• The use of a secondary external streamer tag is

recommended to identify potential transmitter effects and

assess an individual's overall post-tagging condition during

recapture events

• Researchers conducting acoustic tagging studies along the

Atlantic coast should become members of the ACT Network

• Future tagging studies could identify:

• Additional in-river habitats to protect during spawning

events

• Pre- and post-spawn coastal migration patterns

• Overwintering areas leading to the protection of critical

marine habitats

• Only received coastal tag returns for blueback herring (2

males and 2 females)

• All returns were from the Northeast Atlantic spanning from the

south shore of Long Island, NY to Penobscot Bay, Maine

(Figure 4)

Methods

• Study design consisted of the gastric implantation (Figure 1)

of Vemco® V7-4L tags into 25 river herring (13 Alewives and

12 Bluebacks)

• Majority of both species experienced some degree of fallback

following tagging events (Figure 3)

• Female alewives appeared to be more affected by tagging

events than male alewives or either sex of blueback herring

• Majority experienced fallback without returning or attempting

to return to the spawning grounds (Terminal Fallback)

• May be an artifact of location and timing of tagging events

• Alewives were tagged on the spawning grounds and were

in spawning condition (ripe and flowing)

Figure 2. River herring that “disappeared” during the study. The red

boxes indicate areas of heavy harvest from both commercial and

recreational fishers.

• Mean post-tagging residence times differed significantly

(p<.019) between sexes of alewives

• Females: 14.0 days

• Males: 22.5 days

• Both species exhibited rapid post-spawn emigration behavior

however, bluebacks emigrated at a significantly (p<.0004)

faster rate

• Alewives: 5.7 days

• Bluebacks: 3.3 days

0

20

40

60

80

100

120

140

160

180

200

220

240

4/16/2013 4/30/2013 5/14/2013 5/28/2013

Riv

er

Kilo

mete

r

Recreational

striped bass

fishery/drift gill

net

commercial

fishery

Fixed gill net

commercial

fishery

Figure 3.Typical post-tagging behaviors of alewives (top) and

bluebacks (bottom). Detections below river kilometer 0 were from

receivers in NY Harbor and along the south shore of Long Island.

Terminal Fallback

Post-tagging residence time

Rap

id E

mig

rati

on Fallback

Initial Tagging Event

Stationary Receiver Federal Dam-Troy, NY

Spawning Grounds

Confluence of Hudson River

Introduction

Study Objectives:

• Identify handling/tagging effects resulting from tagging

events

• Identify gross in-river movements and residence time during

spawning events

• Identify post-spawn coastal migration patterns