Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bucking Conventional Wisdom, Researchers Find Black Sea Bass Tougher Than Expected

12.03.2014

In a new study, fisheries researchers from North Carolina State University found that black sea bass (Centropristis striata) can usually survive the physical trauma that results from being hauled up from deep water then released at the surface. The finding is part of a larger study of the fish’s mortality rate, which will inform stock assessments designed to help ensure that the black sea bass fishery is sustainable.

Black sea bass are bottom-dwelling fish, and are often caught at depths of greater than 60 feet. When the fish are brought to the surface, the rapid change in pressure causes the fish’s swim bladder to expand. This forces other organs out of the way and can result in visible “barotrauma” – such as the fish’s stomach being forced partially out of its mouth.


Black sea bass with barotrauma (note stomach protruding from mouth). Click to enlarge. Photo: Jeff Buckel

Conventional wisdom long held that this sort of visible barotrauma meant that a fish would die when thrown back into the water. But that’s not true, according to the NC State study.

The research team was attempting to develop accurate estimates of “discard mortality” rates for black sea bass, meaning that they wanted to know what percentage of the fish would die if they were caught and thrown back. Discard mortality rates are used to make informed stock assessments for fish species, because it helps fisheries officials understand how many fish that are caught and released can be expected to survive. Black sea bass are a valuable species for commercial fishing and are also popular with recreational anglers. Millions of black sea bass are caught and released by recreational anglers off the south Atlantic coast of the U.S. each year.

The researchers came up with a novel method for determining the discard mortality rate for black sea bass. First, the researchers worked with a team of scuba divers to tag black sea bass in their natural habitat on the ocean floor. Then the researchers caught, tagged and released the same number of black sea bass in the same area on the same day. The fish tagged on the bottom served as a control group, since they were not subject to changes in atmospheric pressure or other injuries that could be incurred when caught and brought to the surface.

Over the next year, tagged black sea bass were caught by the researchers, or by recreational anglers or commercial fishing operations who returned the tags to the researchers. Researchers could then compare the number of tags returned from the experimental group (those tagged on the surface) to those returned from the control group (those tagged on the bottom). This allowed them to determine discard mortality rates.

The researchers had put the fish in the experimental group into one of four categories: those without visible injury; those with visible barotrauma; those with hook trauma (meaning the hook had caused significant internal injury); and “floaters” – those that couldn’t swim down into the water at all.

To their surprise, the researchers found that approximately 90 percent of the fish in the experimental group with visible barotrauma (but that weren’t floaters) survived. This was about the same survival rate as for fish that exhibited no visible injury at all. Fish with hook trauma had a survival rate of 36 percent, while floaters had a 16 percent survival rate.

“In previous work, estimates of discard mortality were limited to time periods soon after release,” says Paul Rudershausen, a research associate at NC State’s Center for Marine Sciences and Technology and lead author of a paper describing the research. “By tagging a control group, we were able to estimate the long-term effects of injuries associated with fishing.”

In addition to lending key insight into the black sea bass fishery, Rudershausen notes that the study “may give us insight into mortality for other important species with similar characteristics, such as red grouper and gag grouper.”

The paper, “Estimating reef fish discard mortality using surface and bottom tagging: effects of hook injury and barotrauma,” is forthcoming from the Canadian Journal of Fisheries and Aquatic Sciences. The paper was co-authored by Dr. Jeff Buckel and Dr. Joe Hightower, professors of applied ecology at NC State. The researchers worked closely with fisherman Tom Burgess on the project. The work was done under North Carolina Sea Grant Fishery Resource Grant projects 07-FEG-01 and 11-FEG-04.

-shipman-

Note to Editors: The study abstract follows.

“Estimating reef fish discard mortality using surface and bottom tagging: effects of hook injury and barotrauma”

Authors: P. J. Rudershausen, J. A. Buckel, and J.E. Hightower, North Carolina State University

Published: forthcoming, Canadian Journal of Fisheries and Aquatic Sciences

DOI: 10.1139/cjfas-2013-0337

Abstract: We estimated survival rates of discarded black sea bass (Centropristis striata) in various release conditions using tag–recapture data. Fish were captured with traps and hook and line from waters 29–34m deep off coastal North Carolina, USA, marked with internal anchor tags, and observed for release condition. Fish tagged on the bottom using SCUBA served as a control group. Relative return rates for trap-caught fish released at the surface versus bottom provided an estimated survival rate of 0.87 (95% credible interval 0.67–1.18) for surface-released fish. Adjusted for results from the underwater tagging experiment, fish with evidence of external barotrauma had a median survival rate of 0.91 (0.69–1.26) compared with 0.36 (0.17–0.67) for fish with hook trauma and 0.16 (0.08–0.30) for floating or presumably dead fish. Applying these condition-specific estimates of survival to non-tagging fishery data, we estimated a discard survival rate of 0.81 (0.62–1.11) for 11 hook and line data sets from waters 20–35m deep and 0.86 (0.67–1.17) for 10 trap data sets from waters 11–29 m deep. The tag-return approach using a control group with no fishery-associated trauma represents a method to accurately estimate absolute discard survival of physoclistous reef species.

Matt Shipman | EurekAlert!

Further reports about: Black atmospheric pressure black sea bass experimental fishing mortality species

More articles from Ecology, The Environment and Conservation:

nachricht The causes of soil consumption
14.06.2016 | Schweizerischer Nationalfonds SNF

nachricht Fishing prohibitions produce more sharks along with problems for fishing communities
09.06.2016 | Wildlife Conservation Society

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Optical lenses, hardly larger than a human hair

3D printing enables the smalles complex micro-objectives

3D printing revolutionized the manufacturing of complex shapes in the last few years. Using additive depositing of materials, where individual dots or lines...

Im Focus: Flexible OLED applications arrive

R2D2, a joint project to analyze and development high-TRL processes and technologies for manufacture of flexible organic light-emitting diodes (OLEDs) funded by the German Federal Ministry of Education and Research (BMBF) has been successfully completed.

In contrast to point light sources like LEDs made of inorganic semiconductor crystals, organic light-emitting diodes (OLEDs) are light-emitting surfaces. Their...

Im Focus: Unexpected flexibility found in odorant molecules

High resolution rotational spectroscopy reveals an unprecedented number of conformations of an odorant molecule – a new world record!

In a recent publication in the journal Physical Chemistry Chemical Physics, researchers from the Max Planck Institute for the Structure and Dynamics of Matter...

Im Focus: 3-D printing produces cartilage from strands of bioink

Strands of cow cartilage substitute for ink in a 3D bioprinting process that may one day create cartilage patches for worn out joints, according to a team of engineers. "Our goal is to create tissue that can be used to replace large amounts of worn out tissue or design patches," said Ibrahim T. Ozbolat, associate professor of engineering science and mechanics. "Those who have osteoarthritis in their joints suffer a lot. We need a new alternative treatment for this."

Cartilage is a good tissue to target for scale-up bioprinting because it is made up of only one cell type and has no blood vessels within the tissue. It is...

Im Focus: First experimental quantum simulation of particle physics phenomena

Physicists in Innsbruck have realized the first quantum simulation of lattice gauge theories, building a bridge between high-energy theory and atomic physics. In the journal Nature, Rainer Blatt‘s and Peter Zoller’s research teams describe how they simulated the creation of elementary particle pairs out of the vacuum by using a quantum computer.

Elementary particles are the fundamental buildings blocks of matter, and their properties are described by the Standard Model of particle physics. The...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Conference ‘GEO BON’ Wants to Close Knowledge Gaps in Global Biodiversity

28.06.2016 | Event News

ERES 2016: The largest conference in the European real estate industry

09.06.2016 | Event News

Networking 4.0: International Laser Technology Congress AKL’16 Shows New Ways of Cooperations

24.05.2016 | Event News

 
Latest News

Building a better battery

29.06.2016 | Life Sciences

New way out: Researchers show how stem cells exit bloodstream

29.06.2016 | Life Sciences

Crucial peatlands carbon-sink vulnerable to rising sea levels

29.06.2016 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>