Interesting comments on “How do salmon achieve that growth spurt once at sea?”

Posted on by TheFishVet - Richmond's School of Fish

I received some interesting anecdotal comments on my previous blog (www.thefishvet.com) via LinkedIn and would like to share with you.

“A lot of mumbo jumbo for those uninitiated in science speak, but the summary [of the scientific article] is that there are hormonal changes help them to very efficiently convert everything they eat into growth during the spring/summer period.  (link to the original post)”

  • Kabir ChowdhuryKabir Chowdhury Very interesting! Although we suspected the prioritization of the resources consumed in fishes, this article clearly describes the physiological changes inside the animal responsible for the variations in resource allocations. Could similar changes happen in any other migratory species? Or in any other species in response to the seasonal environmental modulations? Any reference?
  • Richmond LohRichmond Loh This same thing could happen in other species too. Rainbow trout show a similar growth pattern, but not to the same extent as Atlantic salmon.
  • Dominique BureauDominique Bureau Anecdotal evidence but we have seen the same significant increase in growth when moving Atlantic salmon, held in fresh water for their entire life cycle and that went through smoltification ( incomplete), from small tanks to much larger tanks. It was not compensatory growth. I always though that vision played a role.
  • Richmond LohRichmond Loh Are you saying that the salmon have their growth spurt even if left in freshwater?
  • Dominique BureauDominique Bureau I have to be cautious since we did not systematically and specifically study this issue. However, we did observed very significant improvement in the growth rate (expressed as TGC) in two or three experiments with a wild Atlantic salmon strain (LaHave River) held in freshwater when we moved the fish to larger tanks.

Eureka moment in crown of thorns starfish fight | News.com.au

Posted on by TheFishVet - Richmond's School of Fish

More on the war against the crown of thorns.

http://mobile.news.com.au/travel/news/eureka-moment-in-starfish-fight/story-e6frfq80-1226490688221

Scientists inject ‘Bovril-like’ hope into reef starfish fight – ABC News (Australian Broadcasting Corporation)

Posted on by TheFishVet - Richmond's School of Fish

http://www.abc.net.au/news/2012-10-08/scientists-inject-bovril-like-hope-into-reef-starfish-fight/4300530

Fish-e Trivia for Monday-itis.

Posted on by TheFishVet - Richmond's School of Fish

What do you call a pregnant goldfish?

You don’t call it anything because goldfish do not get pregnant! They are egg scatterers and fertilisation occurs outside of the body. Fish that are very full of eggs can be called “gravid”.

How do salmon achieve that growth spurt once at sea?

Posted on by TheFishVet - Richmond's School of Fish

A lot of mumbo jumbo for those uninitiated in science speak, but the summary is that there are hormonal changes help them to very efficiently convert everything they eat into growth during the spring/summer period.

 

Aquaculture
  Volume 363, Number 8 (September 2012)
     Growth, osmoregulation and endocrine changes in wild Atlantic salmon smolts and post-smolts during marine migration
   Authors: Sigurd O. Stefansson, Monika Haugland, Björn Thrandur Björnsson, Stephen D. McCormick, Marianne Holm, Lars O.E. Ebbesson, Jens Chr. Holst, Tom O. Nilsen
   Author Affiliations:
no affiliations available
   Source: Aquaculture, Volume 363, Number 8 (September 2012)
   Page Numbers: 127 – 136
   Available Full Text:
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   Abstract: We have examined physiological parameters associated with seawater adaptability, growth and energetics, as well as major endocrine regulators of these processes in wild migrating Atlantic salmon smolts and post-smolts from the river through the fjord, coastal areas and the open ocean. Muscle RNA/DNA ratio suggests that growth rate increases soon after entry into seawater and continues to increase after the post-smolts reach the offshore banks and the feeding grounds in the Norwegian Sea. Post-smolts prioritize rapid growth and protein deposition in spring and summer, and their energy intake during this period is so high that deposition of energy is possible in addition to muscle growth. An increase in thyroxine (T4) and triiodothyronine (T3) levels was observed, suggesting a major activation of hepatic conversion of T4to T3in post-smolts in seawater, probably related to the high metabolic activity and rapid growth and development of the post-smolts. Decreased plasma growth hormone (GH) levels were observed from the river through the fjord, with levels around 2ngml-1in rapidly growing post-smolts, concurrent with an increase in circulating insulin-like growth factor I (IGF-I). An increase in pituitary GH expression levels and hepatic GH receptor (GH-R) and local IGF-I mRNA levels suggest a physiological basis for the changes in circulating GH and IGF-I levels. Receptor expression in brain and pituitary suggests that both hormones are actively involved in the growth and differentiation of these tissues during the critical early marine phase. Gill Na+,K+-ATPase (NKA) activity increased to post-smolt levels above 20µmol ADP mgprot.÷1h÷1, probably representing long-term NKA activity levels of Atlantic salmon in seawater. Concurrent with the changes in NKA activity the expression of the NKA a1b isoform remained high in post-smolts, while the expression of the NKA a1a decreased from smolts to post-smolts. Both cystic fibrosis transmembrane conductance regulator (CFTR) I and II showed a reduction in mRNA levels from smolts to post-smolts, and remained stable at low expression levels in seawater.
   Citation: Sigurd O. Stefansson, Monika Haugland, Björn Thrandur Björnsson, Stephen D. McCormick, Marianne Holm, Lars O.E. Ebbesson, Jens Chr. Holst, Tom O. Nilsen . Growth, osmoregulation and endocrine changes in wild Atlantic salmon smolts and post-smolts during marine migration. Aquaculture, Volume 363, Number 8 (September 2012), pp. 127-136, <http://ejournals.ebsco.com/direct.asp?ArticleID=4BB787BD8A151B2092BC&gt;
   URL: http://ejournals.ebsco.com/direct.asp?ArticleID=4BB787BD8A151B2092BC

Lighting colour, moulting and growth in prawns – their relationship.

Posted on by TheFishVet - Richmond's School of Fish

Anyone who has cultured or kept crustacea will know that the animals seem to “grow” much larger after immediately after moulting and nothing much seems to happen in between. This clever experiment demonstrates how different coloured lights can play a role in growth rates and moulting frequency. Such experimentation will become more practical if/when shrimp culture migrates to the predicted “super-intensive” systems.

Aquaculture
  Volume 363, Number 8 (September 2012)
     Effect of periodic light color change on the molting frequency and growth of Litopenaeus vannamei
   Authors: Biao Guo, Yingchun Mu, Fang Wang, Shuanglin Dong
   Author Affiliations:
no affiliations available
   Source: Aquaculture, Volume 363, Number 8 (September 2012)
   Page Numbers: 67 – 71
   Available Full Text:
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   Abstract: Six color treatments Yellow light (Y), Green light (G), Blue light (B), Blue light to Yellow light (BY), Blue light to Green light (BG), Green to Yellow light (GY) were tested to determine if light color change can promote the growth of Litopenaeus vannamai. After a 45-day experiment, shrimp in BG treatment showed the best weight gain (WG) and the specific growth rate (SGRd), which might have been caused by high food conversion efficiency (FCEd), lowest energy allocation for respiration and highest energy allocation for growth. The molting frequency in GY treatment was the highest, but the growth was not the best. These results suggest that the periodic fluctuation from blue region of the spectrum to green region of the spectrum could promote the growth of L. vannameiand this periodic light color fluctuation may be used as a pattern of regulation of light color in the commercial shrimp culture.
   Citation: Biao Guo, Yingchun Mu, Fang Wang, Shuanglin Dong . Effect of periodic light color change on the molting frequency and growth of Litopenaeus vannamei. Aquaculture, Volume 363, Number 8 (September 2012), pp. 67-71, <http://ejournals.ebsco.com/direct.asp?ArticleID=4CD28768DFA6A9DD42E9&gt;
   URL: http://ejournals.ebsco.com/direct.asp?ArticleID=4CD28768DFA6A9DD42E9

What’s your microscopic gill score?

Posted on by TheFishVet - Richmond's School of Fish

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A novel approach to monitor fish health in fish farms is proposed in this study.

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Aquaculture International: Journal of the European Aquaculture Society
Volume 20, Number 5 (October 2012)
Development of a novel histopathological gill scoring protocol for assessment of gill health during a longitudinal study in marine-farmed Atlantic salmon (Salmo salar)
Authors: Susan Mitchell, Emily Baxter, Celia Holland 1, Hamish Rodger 2
Author Affiliations:
1: Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
2: Vet-Aqua International, Oranmore Business Park, Oranmore, Co. Galway, Ireland
Source: Aquaculture International: Journal of the European Aquaculture Society, Volume 20, Number 5 (October 2012)
Page Numbers: 813 – 825
Available Full Text:
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Authentication: EBSCOhost EJS
Abstract:
Abstract

Gill health and disease in farmed Atlantic salmon (Salmo salar) were studied at a marine site on the west coast of Ireland. Fish were sampled on a regular basis during the summer and autumn of 2009. A novel histopathological scoring system was devised to give a semi-quantitative measure of gill pathology. The index criteria for gill histopathology were lamellar hyperplasia, lamellar fusion, circular anomalies (necrosis or sloughing) and lamellar oedema, a score from 0 to 3 being assigned for each parameter. Ancillary criteria, such as hypertrophy, haemorrhage and the presence of specific pathogens, were assigned a score of 0 or 1. Environmental monitoring undertaken included zooplankton and phytoplankton sampling, as well as temperature and oxygen recordings for the site. Epitheliocystis was frequently observed at low levels but was not associated with any significant gill pathology. Clinically significant gill pathology was observed on one occasion during the sampling period, coinciding with the occurrence of Pelagia noctiluca, Muggiaea atlantica and Solmaris corona. Throughout the longitudinal study, the scoring system provided an accurate and effective means of assessing gill health, demonstrating the ability of this practical tool to be used in future studies of gill health and disease.
Citation: Susan Mitchell, Emily Baxter, Celia Holland, Hamish Rodger . Development of a novel histopathological gill scoring protocol for assessment of gill health during a longitudinal study in marine-farmed Atlantic salmon (Salmo salar). Aquaculture International: Journal of the European Aquaculture Society, Volume 20, Number 5 (October 2012), pp. 813-825, ;
URL: http://ejournals.ebsco.com/direct.asp?ArticleID=40A1A28A3F7E34A78647

What are Pelvic fins used for?

Posted on by TheFishVet - Richmond's School of Fish

Pelvic fins are the paired find that appear on the ventral aspect of many fishes. They’re mainly used as a rudder to help steer the fish.

Some fish such as the female Corydoras use them to cup the eggs they have just laid, holding them in position until they get milt from the males to fertilise them.

Some fish such as the gobies use these find as ‘suction cups’, attaching themselves to smooth surfaces so that don’t have to swim all the time.

However, some fishes such as the gouramis have their pelvic fins in a rather anterior position, and they don’t even look like fins! Instead, they are so very elongate and are so modified that they serve the function of “feelers”! Check them out, checking each other out, the next time you’re in the aquarium store.

Do you know other functions fish have for these pelvic fins? Please do share them.

20121008-120403.jpg

Stunning Salmon – With a Focus on Welfare and Quality.

Posted on by TheFishVet - Richmond's School of Fish

From AquavetMed:

NORWAY – Nofima [the Norwegian Institute of Food, Fishery and Aquaculture] and the Fishery and Aquaculture Industry Research Fund (FHF) held a meeting on the stunning and slaughter of salmon. The focus was on knowledge and experience among participants. The meeting in Tromso, 18 September, saw approximately 60 people from salmon slaughterhouses, aquaculture, scientists, fisheries and equipment. There was great enthusiasm, and participants shared experiences and knowledge.

Although most salmon slaughterhouses has anesthetic and killing systems that work very well, there are still problems that are not solved. The industry reports that the residual blood in the gills and the fish is a growing challenge. This is an element that can affect the quality and shelf life of the fish. A controlled or optimised flow of fish through the slaughter line were seen as the most important for maintaining good welfare and quality.

Experiences from the use of electricity anesthesia has shown that uniformity of fish – i.e. head first – is important, and works well as it is now. Problems with blood spots are practically gone after the plants were built. For the use of electrical anesthesia, researchers recommend the use of voltage of 110 volts with a contact time of five seconds as a good practice. Good fish welfare is a prerequisite for the success of impact machines, which give positive effects if one wants pre-rigor filleting.

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The alternatives to anesthesia with CO2 are now in place in a majority of slaughterhouses. Some butchers still use CO2, but they are all in the process of installing new solutions. At the meeting in Tromsø, it emerged that there have been major challenges for those using the new technology, but that it should be possible to achieve proper stunning and slaughter at all facilities. It is also encouraging to note that there is a high degree of agreement between what industry, equipment suppliers, veterinarians, FSA and researchers think about the status of slaughter.

See the source (http://tinyurl.com/8jc9ynt) for the full story.

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