Dataset: dogfish_mortality
Deployment: NEC-ST2005-1

Spiny dogfish discard mortality using commercial hook gear - Gulf of Maine and Cape Cod, 2006

Co-Chief Scientist:

Lara Slifka (Cape Cod Commercial Fishermen's Alliance, CCCFA)

Dr Shelly Tallack (Gulf of Maine Research Institute, GMRI)

BCO-DMO Data Manager:

Nancy Copley (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Northeast Consortium: Cooperative Research (NEC-CoopRes)

Current State:

Final no updates expected

Version Date:

2010-10-19

Data URL:

https://www.bco-dmo.org/dataset-deployment/452446/data

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Description

Industry-science partnership investigating the short-term and long-term discard mortality of spiny dogfish using commercial hook gear in the Gulf of Maine.

Co-P.I.'s:
Shelly Tallack (Gulf of Maine Research Institute)
Lara Slifka (Cape Cod Commercial Hook Fishermen's Association)

Final Report

Abstract

The unpopular spiny dogfish, Squalus acanthias, represents a resource which, in recent years, despite its apparent high abundance, is considered vulnerable to overfishing. This vulnerability hinges on its characteristics of slow growth, late maturation (~6 years in males and ~12 years in females), high maximum age (35-40 years) and low natural mortality (M=0.09). One immediate problem faced by fishery managers is that while spiny dogfish are periodically caught in high numbers as bycatch (during both recreational and commercial trips), there is little information regarding the survivability of the discarded dogfish. Two recent studies have addressed dogfish discard survival from trawl gear and gillnet gear; the current study addresses survival from commercial hook gear.

This collaborative project represents a partnership between the Gulf of Maine Research Institute (GMRI), the Cape Cod Commercial Hook Fishermen's Association (CCCHFA) and commercial fishermen working with each organization in Gulf of Maine waters and Southern New England waters, respectively. The primary research objective was to investigate the short-term discard mortality rate of dogfish from different commercial hook gears. Survivability was investigated through caging studies.

Methods & Sampling

Dataset acquisition description

A total of 2,418 dogfish were sampled between the two regions; of these 682 were caged by GMRI (45% males and 55% females) and 1,234 were caged by CCCHFA (27% males and 73% females). Dogfish were subject to three gear/handling treatments: 1) snubbed, 2) unsnubbed and 3) control. An overall regional difference in short-term discard mortality was observed; GMRI recorded significantly lower total mortality (7%) than CCCHFA (22%). Regional, averaged findings showed a sex effect with males demonstrating higher mortality (26%) than females (14%). The largest dogfish of each sex demonstrated greater resilience to mortality. Treatment effects were observed with mortality being highest in snubbed fish (23%), then unsnubbed fish (16%) and finally control fish (13%). Gear effects were found with highest mortality resulting from long-line gear (22%) while the different hand gear-related mortality ranged from 8-17%. The relationship between hook removal treatment and hooking severity index (HSI) was significant; severe mouth and jaw injury was most frequent in snubbed fish but was rare in control fish and the overall trend was that mortality increased with increased HSI.

Considerable variation was observed between the GMRI and CCCHFA findings; this variation was likely caused by differences in: water temperature, levels of parasitic infestation (i.e. sand fleas) and possible differences in handling, tanking and caging procedures. This study's long-term discard mortality assessments were aborted for logistical reasons and as such, these findings represent the range of likely short-term discard mortality from hook gears across the region.

Data Processing Description

Dataset Processing Description

More information about this dataset deployment

Funding

Award Number	Funding Source
PZ07009	National Oceanic and Atmospheric Administration

Instruments

Electronic Jig Machine

Supplied Description:

Instrument Type

Generic Name: Electronic Jig Machine

Acronym: eJig

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/90/

Generic Description:

An electronic jig machine is used to mechanically jig a fish hook or lure with a bait casting reel without using the fishing rod to jig the lure. Normally to jig a fish hook or lure one must move the fishing rod either vertically, horizontally, or jerk the fishing line by hand. The jigging action of this bait cast reel (how rapid and how long in distance the jig will travel) will determine the desired intensity and resonance of the rattle used in the lure to attract or snag the fish. With very simple controls, the equipment functions automatically since it is programmed to suit the actual fishing area, the fishing method and the type of fish.

Fish Cage

Supplied Description:

Instrument Type

Generic Name: Fish Cage

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/90/

Generic Description:

Used to catch fish.

Fishing Rod

Supplied Description:

Instrument Type

Generic Name: Fishing Rod

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/90/

Generic Description:

Used to catch fish.

Longline Fishing Gear

Supplied Name: Long Line Fishing Gear

Supplied Description:

Instrument Type

Generic Name: Longline Fishing Gear

Acronym: Longline

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/90/

Generic Description:

Longlining employs a central fishing line that can range from one to 50 miles long; this line is strung with smaller lines of baited hooks, dangling at evenly spaced intervals. Longlines can be set near the surface to catch pelagic fish like tuna and swordfish, or laid on the sea floor to catch deepdwelling fish like cod and halibut. (www.montereybayaquarium.org/cr/cr_seafoodwatch/sfw_gear.aspx)

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
region	Gulf of Maine or off Cape Cod. Mass.		region
cruiseid	vessel name plus trip number		cruiseid
month_local	month of year, local time		month_local
day_local	day of month, local time		day_local
yrday_local	local day and decimal time, as 326.5 for the 326th day of the year, or November 22 at 1200 hours (noon)		yrday_local
haul_num	haul number		no_bcodmo_term
lat_start	latitude at starting time of measurement (west is negative), in decimal degrees	decimal degrees	lat_start
lon_start	longitude at starting time of measurement (west is negative), in decimal degrees	decimal degrees	lon_start
lat_end	latitude at end time of measurement; in decimal degrees (negative denotes South)	decimal degrees	lat_end
lon_end	longitude at end time of measurement; in decimal degrees (negative denotes West)	decimal degrees	lon_end
count	sequential number of dogfish caught during a haul		count
tagid	fish identification tag number		tagid
sex	male or female		sex
length_cm	Length of fish from tip of nose to end of tail in centimeters	centimeters	length
weight_g	Weight of fish in grams		weight_g
init_fate	Fate of fish when it went into cage (A=alive, D=dead)		no_bcodmo_term
stamina_haul_code	Stamina level when fish was taken off hook (1-4, 1=strong, 4=dead)		no_bcodmo_term
stamina_cage_code	Stamina level when fish went into cage (1-4, 1=strong, 4=dead)		no_bcodmo_term
init_hook_severity_code	Hooking severity index upon caging (0-5, 0=hooked inside, 1=small hole, 5=broken jam, large hole)		no_bcodmo_term
hook_site_code	Site where hook punctured fish: 1=mouth, 2=cheek, 3=eye, 4=nose, 5=inside mouth, 6=swallowed, 7=gills, 8=tail		no_bcodmo_term
male_maturity	Stage of reproductive maturation if fish was a male and it was obvious from external viewing		no_bcodmo_term
female_maturity	Stage of reproductive maturation if fish was a female and it was obvious from external viewing		no_bcodmo_term
fish_treatment	What treatment this fish endured (S=snubbed, U=unsnubbed or C=control)		no_bcodmo_term
gear_method	What type of gear was used to catch this fish (LL=longline, R=rod, J=jig, RJ=rod or jig, HL=handline)		no_bcodmo_term
fate_final	Coded Final Fate category: 0 = Dead, 1 = Alive, 2 = escaped, 3 = died in tank, 4 = released		no_bcodmo_term
stamina_final	Final Stamina Index of fish when it was retrieved on it's last day(includes noncaged and longterm fish): (1-4, 1=strong, 4=dead)		no_bcodmo_term
hook_severity_final	Hooking severity index upon retrieval (0-5, 0=hooked inside, 1=small hole, 5=broken jam, large hole)		no_bcodmo_term
comments_fish_initial	Any relevant comment about this fish upon retrieval		no_bcodmo_term
tank_duration	How long the fish was in the tank	minutes	no_bcodmo_term
sample_type	What sample group this fish belongs to: 1=caught only, 2=caught and caged, 3=caught, caged and used in mortality sample, 4=unknown if caged, not used in mort sample		no_bcodmo_term
comments_fish_final	Any relevent comment about this fish upon retrieval		no_bcodmo_term

Database

Contribute Data

Dataset: dogfish_mortality
Deployment: NEC-ST2005-1

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: dogfish_mortalityDeployment: NEC-ST2005-1

Dataset acquisition description

Dataset Processing Description

Dataset: dogfish_mortality
Deployment: NEC-ST2005-1