Science corner: latest fish & fisheries research

[John F]

Starting this thread to share some interesting and relevant published research on fish and fisheries....


Enjoy!

[John F]

Response to ocean acidification in larvae of a large tropical marine fish, Rachycentron canadum

* Currently, ocean acidification is occurring at a faster rate than at any time in the last 300 million years, posing an ecological challenge to marine organisms globally;

*  There is a critical need to understand the effects of acidification on the vulnerable larval stages of marine fishes, as there is potential for large ecological and economic impacts on fish populations and the human economies that rely on them;

*  Larval cobia were raised through the first 3 weeks of ontogeny under conditions of predicted future ocean acidification to determine effects on somatic growth, development, otolith formation, swimming ability, and swimming activity;

* Cobia exhibited resistance to treatment effects on growth, development, swimming ability, and swimming activity;

* However, these scenarios resulted in a significant increase in otolith size (up to 25% larger area) at the lowest pCO2
levels reported to date, as well as the first report of significantly wider daily otolith growth increments.

* When raised under more extreme scenarios of 3500 and 5400, cobia exhibited significantly reduced size-at-age (up to 25% smaller) and a 2–3 days developmental delay;

* The robust nature of cobia may be due to the naturally variable environmental condi tions this species currently encounters throughout ontogeny in coastal environments, which may lead to an increased acclimatization ability even during long-term exposure to stressors.


Those interested in reading the full paper please let me know.

Reference:
Bignami, S., S. Sponaugle & R. K. Cowen (2013). Response to ocean acidification in larvae of a large tropical marine fish, Rachycentroncanadum. Global Change Biology, 19: 996-1006.

[WalkersKiller]

Nice thread, hope to add something useful here soon!

[PH]

Thanks Marcos. Is it known why ocean acidification is accelerating?

[John F]

Yes, increase of CO2 in the atmosphere, which dissolves in the water and form carbonic acid. This is an emergent line of research as it has huge implications for tropical countries. As you know coral reefs are basically calcium carbonate deposits. Ocean acidification basically means all carbonate will be dissolved. No more coral reefs. The socio-economic consequences are simply catastrophic!

[PH]

That is damn scary!
"We civilse left, we civilse right....."

[John F]

Genetic divergence between populations of Lichia amia

* Lichia amia is an important coastal recreational fishery species with a cosmopolitan distribution in the eastern
Atlantic. In southern Africa, it is distributed from southern Angola to northern KwaZulu-Natal in South Africa.

* A recent biological survey revealed differences between Angolan and South African individuals suggesting that they
may represent separate stocks.

* As fishery management decisions should be based on accurate knowledge of population structure, an initial survey of the genetic substructuring of L. amia was conducted on samples collected in southern Angola and South Africa.

* Two deeply divergent (southern Angolan and South African) populations were identified across the Benguela Current system.

* The results suggest that Angolan and South African L. amia should be managed as two independent stocks.


PDF available. Those interested please send me a PM.


Reference

Henriques, R., W. M. Potts, W. H. H Sauer & P. W. Shaw (2012). Evidence of deep genetic divergence between populations of an important recreational fishery species, Lichia amia L. 1758, around southern Africa. African Journal of Aquatic Science, 34: 585-591.

[John F]

Ingestion of plastic marine debris by longnose lancetfish (Alepisaurus ferox) in the North Pacific Ocean

* Plastic marine debris affects species on most trophic levels, including pelagic fish;

* While plastic debris ingestion has been investigated in planktivorous fish in the North Pacific Ocean, little knowledge exists
on piscivorous fish;

* The objectives of this study were to determine the frequency of occurrence and the composition of ingested plastic marine debris in longnose lancetfish (Alepisaurus ferox), a piscivorous fish species captured in the Hawaii-based pelagic longline fishery.

* Nearly a quarter (47 of 192) of A. ferox sampled contained plastic marine debris, primarily in the form of plastic fragments (51.9%);

* Further research is needed to determine residence time of ingested plastic marine debris and behavior of toxins associated with plastic debris.


Reference

Jantz, L. A., C. L. Morishige, G. L. Bruland & C. A. Lepczyk (2013). Ingestion of plastic marine debris by longnose lancetfish (Alepisaurus ferox) in the North Pacific Ocean. Marine Pollution Bulletin, 69: 97-104.

[FishStyx]

Thanks for this thread Marcos.


A question on the Garrick. I was under the impression that the 2 were acknowledged as separate species, the Angolan and upwards being "Tropical Garrick" as opposed to our "Southern Garrick".


Also, what is pCO2?

[John F]

Thanks for this thread Marcos.


A question on the Garrick. I was under the impression that the 2 were acknowledged as separate species, the Angolan and upwards being "Tropical Garrick" as opposed to our "Southern Garrick".


Also, what is pCO2?

So far their are recognized as a single species, although it seems they are following a speciation path into separate species.


pCO2 is the partial pressure of CO2. In the atmosphere, the partial pressure of CO2 is defined as the pressure the CO2 would exert if all other gases were removed. The sum of the partial pressure of all the atmospheric gases will equal the atmospheric pressure.

[FishStyx]

Thanks, I had never heard the term before. Seems one is never too old to learn new stuff.

[John F]

Contribution of a large no-take zone [Pondoland MPA] to the management of vulnerable reef fishes in the South-West Indian Ocean

* This study, based in the South-West Indian Ocean, evaluated the benefits of area closure to vulnerable fishery species, which have been depleted by overfishing.

* A controlled fishing survey was conducted seasonally between 2006 and 2011 in the Pondoland MPA on the East Coast of South Africa. The MPA includes a 400 km2 no-take zone where all forms of vessel-based exploitation are prohibited.

* Three endemic sparids (slinger Chrysoblephus puniceus, Scotsman Polysteganus praeorbitalis and poenskop Cymatoceps nasutus) and one widely distributed serranid (yellowbelly rockcod Epinephelus marginatus) were chosen as study species.

* These are slow growing, high trophic level species, which are prominent on rocky reefs in the Pondoland area and have been depleted by overfishing. Relative abundance was estimated using catch-per-unit-effort (CPUE) and length frequency
distributions were used to determine the size structure of fish populations.

* The relative abundance and the mean length of all four species were significantly greater in the no-take zone.

* Over the 5-year study period, CPUE of C. puniceus and C. nasutus in the no-take zone increased as did the mean length of all
species, except C. nasutus.

* This study presents clear evidence that the Pondoland MPA no-take zone is providing insurance against the depletion of vulnerable fishery stocks in fished areas, thereby establishing the basis for the enhancement of adjacent fisheries.



PDF available. Those interested please send me a PM.

Reference

Maggs, J. Q., B. Q. Mann & P.D. Cowley (2013). Contribution of a large no-take zone to the management of vulnerable reef fishes in the South-West Indian Ocean. Fisheries Research, 144: 38-47.

[REEFMAN]

Amazing how important these MPA's are proving to be! Keep these posts coming Marcos... very interesting!

[Marthin]

100% correct Reefman.  That's why i'm against beachdriving being allowed again... it has created natural MPA's especially in the southern cape for inshore reef species in particular....

Anycase very interesting information.....

[Charles]

Thanks John F! Very informative and great reading.

[Wynand13]

   Something to really monitor! Would you mind mailing me the whole paper?

[John F]

  Something to really monitor! Would you mind mailing me the whole paper?

  email sent.

[Wynand13]

Thank you, what can the average Joe do about this? I have red about people doing strange things to try and counter this, from dumping metal phosphate into the water to try and change the PH... We know we must reduce carbon, but how do we fix the problem? Assume the person with the answer will be a billionaire soon....

[John F]

Like everything else, it's not what ONE individual can do, but the cumulative efforts of millions of ONE's.... this is what, in my opinion, humans still have to realize... gotta learn from bees and ants...

Environmental degradation is rarely caused by the actions of one individual (well, except oil spills and similar)... as a society we need to waste less, recycle/re-use/reduce more. Have less babies and stop thinking about today... every single planning exercise is done on a 4/5 year basis... nature does not operate like that! 

[WalkersKiller]

Awesome info there Marcos!