Fisheries Science - Science topic

Which fish species in Africa are abundantly being harvested?

KC Denmark A/S is a global supplier of equipment. They have a range of Manta nets complete with accessories such as digital flow meters. I have just received a quotation from then.

You may consider visiting their website.

Regards

Think of some indicators (independent variables) like swt, pH, salinity, DO etc and dependent variable like CI of fish (species-wise), distribution, community structure and have a correlation study

David Guerra ..... It is more common to get the confusion with regard to the unit used for some of the vitamins (vit A, D E, etc) and a few Minerals when they are added with the feed. For better understanding of this myth, it is better to keep the following points in mind:

1. IU stands for International Unit, which is totally different from Mg or Mcg... or any measurable mass or volume

2. IU is not to be measured by mass or weight or volume, rather it is used to denote the effect or impact of the particular component at that specific IU

3. IU can be converted to Mg or Mcg.. vice-versa is also possible.. But to be clear that when IU is to be converted to Mg or Mcg, it has to be divided by the Conversion Factor, while the Mg or Mcg is converted to IU, it has to be multiplied by the Conversion Factor...

4. Now it must be clear that, for knowing the volume to be added or incorporated, each IU should be dived by the Conversion Factor to get the Mg or Mcg equivalent.

5. More important point is that each ingredient bearing IU will have different Conversion Factor, e.g., Vit A - Retinol will have a CF different from Beta Carotene... Therefore depending on the ingredient, the CF has to be applied and used.

In extract, it has to be borne in mind that IU is a measure of biological activity of that particular substance and is specific to each substance in a class or group of substances named with the same title...

Hope the above might be of some use to get a clarification...

Dr js....

Dear Alexander P Scott ,

After all those years I was curious to see if the ‘journals’ in your example still exist and what can be said about them:

-The first one “Integrative Gyn(a)ecology and Obstetrics Journal” is published by “Research Open” (https://researchopenworld.com/category/integrative-gynecology-and-obstetrics/) a publisher mentioned in the Beall’s list (https://beallslist.net/). This is a red flag but just by looking at their contact info it is clear that they hide their true location (so deceptive to say the least)

-The second one “SOJ Materials Science and Engineering” is published by “SYMBIOSIS (GROUP LLC)” (https://symbiosisonlinepublishing.com/materialsscience-engineering/) a publisher mentioned in the Beall’s list (https://beallslist.net/). Same here, just look at the contact info and it is clear that this has nothing to do with a ‘corporate’ office (so again they hide something)

-The third one “International Journal of Poultry and Fisheries Sciences” is published by the same publisher (https://symbiosisonlinepublishing.com/poultry-fisheries-science/). This one is discontinued (last issue is from 2018).

It is amazing (and sad) to see that most of them are still there.

Best regards.

PS. Muhammad Shahzaib just search for predatory here on RG and you will get a good impression on how to do spot these fraudsters. As indicated by Omar Hernando Avila-Poveda (Avila-Poveda OH) checking whether the journal has some serious indexing (Scopus etc.) is one approach, checking the Beall’s list is another one. By the way, the examples mentioned by the 'deleted profile' contains numerous examples of so-called hijacked journals (a phenomenon, if possible, even worse than predatory). Just search for hijacked here on RG.

Hi Purnendu. Interesting question. I know this isn't exactly what you were asking for but Ye et al. presents a nice paper on using equation-free state-space reconstruction (i.e., empirical dynamic modelling) to forecast fish population dynamics. @

Pierre Cresson , great paper, I downloaded it early today and then came looking for more info on the conversion subject, and found the author himself :D Thank you!

I found a reference to using compost tea as a foliar spray that increased production. This was from Dr. Salam's group at Bangladesh Agriculture University.

Effects of molasses and compost tea as foliar spray on water spinach (Ipomoea aquatica) in aquaponics system

An experiment was conducted to evaluate the effect of foliar spray with molasses and compost tea on water spinach in aquaponics system. Nutrient Film Technique was employed for water spinach culture under three different treatments with molasses (T1), compost tea (T2) and no spray as control (T3). Tilapia fingerlings, fed on a commercial diet, were reared in the aquaponics system. Waste water from the fish tank was re-circulated through the plant grow bed where nitrifying bacteria resided to convert toxic elements into plant available nutrients and supplied clean water to fish tank in return. 180 days trial revealed that T2 yielded the highest production of 5.56 kg water spinach, followed by T1 (4.73 kg) and T3 (4.39 kg). The average productions of water spinach (2.17 kg/m2/month) and tilapia (22.38 ton/ha/month) with an FCR of 2.33 suggest a prospective use of compost tea and molasses as foliar spray to produce organic vegetables. (Less)

Thank you

By writing keywords: feed industry for fish feed

Note that a number of my research published on the manufacture of fish feed

Azolla, Eichhornia, Cabomba, Aponogeton, Salvinia, Carex, Nymphoides, Pistia, Hydrilla, Lemna, Anacharis, Egeria, Limnophila, Rotala etc can all be used as fish foods in addition to various micro - or macroalgae (though not strictly plants). Blanced cucumber, small pieces of ripened banana, tiny bits of garlic, carrots, soybean etc are all excellent supplements as well (generally not maize or corn). Many otherlocally available edible land plants have been used as fish feed in various fisheries over the years as well.

Yes, I did as part of my Ph.D work, except the gaps in sampling years were sometimes decades. I was able to access river gauges and catch locations for Alosa sapidissima larvae for 3 historic surveys, and add that data to my own 2-year survey. Using several data sets and ordination techniques, I was able to show that the discrepancy in reported spawning locations was due to rainfall levels. The fish shifted many km upriver to a section of river with a greater drop in elevation when river flows were reduced to find their preferred flow rates.

Combining old data sets (carefully!) is actually an important task since few data sets are continuous and no one can afford to discard data if funding disappears for a year or ten!

Hello guys,

Do you know what package in R I can use to calculate the Vanderploeg and Scavia's Electivity Index?

Dear Sue,

Maybe the following recent papers will help you:

Kroodsma DA, Mayorga J, Hochberg T, Miller NA, Boerder K, Ferretti F, et al. Tracking the global footprint of fisheries. Science 2018;359(6378):904-908. https://www.researchgate.net/publication/323126788_Tracking_the_Global_Footprint_of_Fisheries

Lavoie RA, Bouffard A, Maranger R, Amyot M. Mercury transport and human exposure from global marine fisheries. Sci Rep 2018;8(1):6705. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5928114/pdf/41598_2018_Article_24938.pdf

Serpetti N, Baudron AR, Burrows MT, Payne BL, Helaouët P, Fernandes PG, Heymans JJ. Impact of ocean warming on sustainable fisheries management informs the Ecosystem Approach to Fisheries. Sci Rep 2017;7(1):13438. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5647405/pdf/41598_2017_Article_13220.pdf

Cooke SJ, Allison EH, Beard TD Jr, Arlinghaus R, Arthington AH, Bartley DM, et al. On the sustainability of inland fisheries: Finding a future for the forgotten. Ambio 2016;45(7):753-764. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5055481/pdf/13280_2016_Article_787.pdf

Best wishes from Germany,

Martin

Dear Taylor, the group of Robert Arlinghaus (Berlin) has done a lot of research in this field. You may contact him and/or check his reference list here on ResearchGate.

Best regards, Klaus

I have fisheries data for both- migratory and lake smelt Osmerus eperlanus since ~1946- 1947.

Janis

thank you all for your help 

Please give a look at the webpage of EMODnet Mediterranean Checkpoint project. Challenge 5 is dedicated to the fishery management. At the bottom of the page you can find the Targeted Products, in particular look at the MEDSEA_CH5_Product_6 and MEDSEA_CH5_Product_7 produced from AIS data and their GIS visualization.

You can find also the TEAM involved, that you could contact to ask further info about the data availability.

Dear Aasma Noureen

you can assess the tail movement, head length and tail length of comet assay by micrometer (µm) using  the comet score -image analysis Software (TriTek Corp., Sumerduck, VA)  

Thank you Dr. Neethu

Hi Neethu,

attaching some of my articles that include developmental biology, culture, and fisheries

best regards

Deepak

Hello Subburathinam Balakrishnan 

please check the resources

Some freshwater crab species eat dead leaves and algae, while a small number of species are carnivorous. Platythelphusa armata, for example, lives almost exclusively on snails found in Lake Tanganyika. However, most freshwater crabs are not particular about what they eat, and many subsist on the detritus that accumulates at the bottom of rivers, lakes or aquariums.

Freshwater crabs generally live in tropical and subtropical climates, and while many live around bodies of water, some live in caves or even the boles of trees. They usually play integral roles in their ecosystems, with many species serving as a source of food for other animals and as a way of determining water quality for scientists due to their dependency on clean water. Because many species have such specialized habitats, freshwater crabs are also largely endangered; for instance, 40 of the 50 species native to Sri Lanka are threatened. Semi-terrestrial species that require both land and water to live on are most commonly in danger.

Few freshwater crabs are available as pets. Even the mini crab, a kind of fiddler crab commonly sold in pet stores, requires brackish water, meaning it needs at least some salt in its environment. Many species sold in pet stores also require some amount of land in their aquarium. In terms of diet, mini crabs eat bloodworms and brine shrimp, although they will also consume any uneaten fish food that gathers at the bottom.

Thanks for all the useful suggestions and papers.  MPAs are new in Scotland's waters so we will see how those develop in the coming years. As Trevor alludes to, I am thinking more of regional management, where commercial activities in the marine environment are expanding - fisheries, having had unrivalled access to the seas from centuries, now being traded off with other emerging industries (including conservation) and any examples of were this is being well integrated... maybe we are just not there yet? (I will look further into the suggestion here, so thanks again). Scotland has advanced MSP, but we are only just starting to implement this and having to address the significant trade-offs (at this point mainly economic and social) assuming we aim to prioritise and work within environmental limits (assuming we can measure what those are - and one can assume too much!).

Dr. Noori Nasir, thank you for the great advice and info on using probiotics for aquaculture with examples of studies that can be used.

Dear Rajaa, We are conducting similar studies on rough sharks from the Adriatic sea, what species do you study ? Im interested in comparing results. God bless

Dear Kalidah

I attach the search. I wish to be helpful to you

Beast Wishes

Amjed K. Resen

Dear Adel Al- Dubakel

Send your file I hope that you find the answer

BEAST Wishes

Amjed K. Resen

Dear Mahdieh,

In addition to the valuable information provided in the previous answers, please refer to the links below for more detailed information about your question.

Best wishes 

SM Najim

I already have this link but THANK YOU for your contribution.

Regards!

Gilles,

I do not like to respond negatively to suggestions made by others but, I regret, yours are not simply wrong but dangerous. You have echoed mistakes of half a century ago that were comprehensively debunked in the 1980s.

I agree that examining CPUE, species composition and size frequency is an important first step (if Jeewantha's interest is in resource conservation). However, CPUE is a very poor indicator of resource abundance or biomass and its stability is often a very misleading, erroneous "indication" of a stability of the resource that does not exist. Species and size compositions are more sensitive indicators in some fisheries but not in all. Yes, it is worth looking at trends in such data but nobody should suppose that stability in the numbers is a firm indication that all is well.

Conversely, when a fishery is first developed, we expect abundance and biomass to fall dramatically -- often by something between a third and two-thirds. That is the "fishing up" or "fishing down" that theorists have discussed since the 1930s. In the real world, there are also ecological interactions that fishermen respond to, so the initial depletion of an original resource species can lead to a  shift in the composition of catches, as effort concentrates on some alternative that is increasing in abundance to fill a fishery-created void in the trophic structure. In short, if trends in the basic indicators are seen, it does not necessarily show that anything is wrong, just that the resources and the ecosystem are changing from a "virgin" state to one that can support sustained exploitation.

Which leads to a more general point: Determining the status and prospects of a fishery is neither easy nor simple. Far too many people have thought that it is both and that goes a long way to explain the mess that so many fisheries are in today.

In vitro digestibility of water-soluble and water-insoluble protein fractions of some common fish larval feeds and feed ingredients

Hi Charles

The freshwater dip shouldn't kill the host as it is only a temporary osmotic shock. That said, if the hosts are moribund or otherwise compromised then any procedure is going to increase the risk of mortalities. What is the target host species? If you are dealing with a commercial interest then freshwater is probably going to be the most acceptable method as there are obviously no issues with chemical use approvals and retention times. I have used this method repeatedly on a large diversity of species including some very sensitive ones (and juveniles) with good success. Your concerns should be covered under a university ethics approval, which I would imagine would be acceptable to your collaborators? Under all methods they would need to acknowledge some possible mortalities, but that these would be avoided were possible. If I can be of any future assistance please just shout - I am more than happy to help.

Best regards, David

Hi Hilmar,

We do quite a bit of drilling underwater for our monitoring site set up. We have a spitzner drill.

Nemo drill looks good in theory. the video looks pretty convincing. If it has a good hammer action it should work. if not then it is prob useless. we had an old underwater drill with no hammer action and it was ineffective. the spitznas is not too cumbersome. need a few spare cylinders to take down with you or with your buddy. got video of it somewhere if you want to see. let me know if I can help anymore. cheers, Charlie

Sorry,

I wanted to write Fst (pairwise)

Best regards

Hello sambit Kisore Das,

please check the following attachment given below.

2.1.1 Salinity

The difference between fatty acid compositions of marine and freshwater fish has been noted by several authors. Some examples of fatty acid patterns are given in Table 1. Although these fish lipids are higher in w 3 fatty acids, it is clear that freshwater fish have higher levels of w 6 fatty acids than marine species. The average w 6/w 3 ratios are 0.37 and 0.16 for freshwater and marine fish, respectively. Fish in general contain more w 3 than w 6 polyunsaturated fatty acids (PUFA) and should have a higher dietary requirement for w 3 PUFA; thus the dietary EFA requirement of marine fish for w 3 PUFA may be higher than that of freshwater fish.

Table 1 - Comparison of the Fatty Acid Pattern of Total Lipid from Whole Fish or Flesh, from Freshwater and Marine Species 1/

The same type of difference in the w 6/w 3 ratio between freshwater and seawater is seen when some species of fish migrate from oceans to streams or vice versa. The PUFA ratio of sweet smelt (Plecoglosus altivelis) changes drastically in only one month as they migrate from the sea to a freshwater river. A similar but reverse change occurs in the masu salmon (Oncorhynchus masu) as they migrate from freshwater to seawater. Even within the same species of fish, the salinity of the water seems to cause a dramatic change in the fatty acid pattern.

The difference between marine and freshwater fish may be due simply to differences in the fatty acid content in the diet or it may be related to a specific requirement in fish related to physiological adaptations to the environments. The phospholipids are generally considered to be structural or functional lipid, being incorporated to a large extent in the membrane structure of cell and subcellular particles. The triglycerides are more often storage lipids and reflect the fatty acid composition of the diet to a greater extent than do the phospholipids. In Table 2, the fatty acid compositions of the triglyceride and phospholipid fractions of fish lipids are presented. It can be seen that the effect of changing environment on the fatty acid composition of the phospholipid is as great in the case of salmon, and considerably greater in the case of the sweet smelt, than it is on the triglyceride composition. Rainbow trout on diets containing either corn oil, which is high in w 6 but low in w 6 PUFA, showed a higher mortality and growth reduction in seawater than in freshwater over the twelve-week feeding period.

2.1.2 Temperature

There are several other factors besides the salinity of the water which affect the fatty acid composition and especially the PUFA of fish. In Tables 1 and 2 it can be seen that the salmonids, even in freshwater, tend to have a higher total PUFA of the 20 and 22 carbon chain length, and a lower w 6/w 3 ratio than the other fish. The salmonids are mostly cold-water fish. The fatty acids from a number of marine animals from temperate and arctic waters show some significant differences in the general pattern; unfortunately analysis included fatty acids longer than 20:1. There are a number of other experiments demonstrating the effect of environmental temperature on fatty acid composition of aquatic animals. The general trend toward higher content of long chain PUFA at lower temperatures is quite clear. The w 6/w 3 ratio decreases with a decrease in temperature (Table 3). If the trends in fatty acid composition can be taken as clues to the EFA requirements of fish, the w 3 requirement would be greater for fish raised at lower temperatures. Fish raised in warmer waters, such as common carp, channel catfish, and tilapia may do better with a mixture of w 6 and w 3 fatty acids.

2.2 Effects of Diet

Some of the fatty acid compositions listed in Table 3 may be seriously affected by the dietary lipids. The mosquito fish and guppies were fed trout pellets which had an w 6/w 3 ratio of 2.75. The catfish were fed diets supplemented with either beef tallow or menhaden oil, with w 6/w 3 ratios of 18.13 and 0.15, respectively. These fish were able to alter the dietary w 6/w 3 ratio in favour of w 3 fatty acid incorporation into the flesh lipids even at the highest temperature. Commercially available trout pellets are often low in w 3 PUFA and high in w 6 fatty acids. It is important not to ignore the effect of dietary lipid composition on fatty acid composition of fish fed artificial diets. It is clear from the data in Table 3 that the w 6/w 3 ratio of the fish lipids is greatly affected by the w 6/w 3 ratio of the dietary lipids. When the dietary ratio is very high in w 6 fatty acids supplied by animal lard or vegetable oils, there is a tendency for fish to alter the ratio of PUFA incorporated in favour of w 3 fatty acids. When the dietary oil is a fish oil high in to3 fatty acids, there is little change in the w 6/w 3 ratio of lipids incorporated into the fish. This is further suggestive evidence of an EFA requirement of fish for w 3 PUFA.

Table 2 Changes in Fatty Acid Composition of Lipids of Fish as they Migrate from Seawater to Fresh and Vice Versa 1/

Table 3 Effect of Environmental Temperature on Fatty Acid Composition of Fish Lipids 1/

2.3 Seasonal Variation

Seasonal variations in the fatty acid composition of fish species have often been reported. Seasonal changes have been observed in total lipid and iodine values of herring oils. The iodine value or degree of unsaturation of the oil was minimal in April and maximal in June. The great increase in unsaturation corresponded to the onset of feeding in spring. The absence of a gas liquid chromatograph (GLC) at the time precluded identification of changes in individual fatty acids.

Flesh and viscera lipid content of the sardine Sardinops melanosticta vary from 3.9 to 10.77 percent and from 10.9 to 38.3 percent, respectively. The fatty acids of principal interest with respect to EFA metabolism are 20:4w 6, 20:5w 3, and 22:6w 3. There was considerable variation in all of these fatty acids in both neutral and polar lipid from both tissues. In the flesh, the 20:4 w 6 was consistently higher in the neutral lipid than in the polar lipid. The total 20:5w 3 plus 22:6w 3 was consistently higher in polar lipid than in the neutral lipid. Thus, in spite of the major fluctuations in fatty acids caused by changes in diet and temperature throughout the seasons, there was a consistent preferential incorporation of PUFA of the w 3 series into the polar or phospholipid fraction of the lipids.

One of the best clues to the EFA requirements of a species can be gained from the fatty acid composition of the lipids incorporated into the offspring or egg. The act of reproduction or spawning also has a significant effect on the seasonal fluctuation of lipids in fish. Fatty acid composition of fish egg lipids is probably distinctive for each species and contains increased levels of 16:0, 20:4 w 6, 20:5 w 3 and 22:6w 3 compared to the liver lipids of the same female fish (Ackman, 1967).

Elevated levels of 16:0, 20:5w 3, and 22:6 w 3 and reduced 18:1 in the ovary occurred compared to mesenteric fat of Pacific sardine fed a natural copepod diet. The blood fatty acids of the sardine fed the natural diet were similar to those of the ovary. When the sardines were fed trout food, both the blood and mesenteric fat responded to the diet with elevated 18:2w 6 and reduced 20:5w 3 arid 22:6w 3. The effect of the diet on ovary fatty acid content was considerably less, as relatively high levels of 20:5w 3 and 22:6w 3 were retained.

The ovary lipids of the sweet smelt show an increase in 16:0, and a reduction in the PUFA, especially in the phospholipids, compared to the lipids from the flesh of fish caught at the same time of year. The w 6/w 3 ratio of the ovary was lower than that of the flesh lipids, 0.21 and 0.17 for the ovary compared to 0.31 and 0.20 for the triglycerids and phospholipids of the flesh, respectively.

The hatchability of eggs from common carp fed several different formulated feeds is greatly reduced when the 22:6w 3 of the egg lipids is less than 10 percent. Further, the muscle, plasma, and erythrocyte fatty acid compositions are more affected by dietary lipid than those of the eggs.

The EFA requirements of a number of species of fish have been investigated in nutritional studies. The fish themselves have given ample evidence for EFA preference by the types of fatty acids they incorporate into their lipids. Fish, in general, tend to utilize w 3 over w 6. This is especially observed when the dietary lipids are high in w 6, as the fish tend to alter the w 6/w 3 ratio toward the w 3 fatty acids in the tissue lipids. The lipids of the egg must satisfy the EFA requirement of the embryo until it is able to feed. The fatty acid composition data suggest that the w 3 requirement is greater in seawater than in freshwater and higher in cold water than in warm water.

The Catalog of Fishes entry is as follows:

gnanadossi, Ariosoma Talwar [P. K.] & Mukherjee [P.] 1977:432, Fig. 1 [Indian Journal of Animal Sciences v. 47 (no. 7); ref. 27708] Off Madras, India, depth 250 meters. Holotype (unique): ZSI F.7146/2. See Das 2003:350 [ref. 27706]. •Valid as Ariosoma gnanadossi Talwar & Mukherjee 1977 -- (Psomadakis et al. 2015:148 [ref. 34104]). Current status: Valid as Ariosoma gnanadossi Talwar & Mukherjee 1977. Congridae: Bathymyrinae. Distribution: Pakistan and India. Habitat: marine.

We consider the species as valid in CONGRIDAE; the species name, however, should read Ariosoma gnanadossi.

Well, correcting my previous comment, this actually is a Ficobracon sp. as confirmed by van Achterberg.

Pradeep:

At one stage R. jayakari was considered as a Synonym of R. javanica. Since you have access to the actual specimen, you need to carefully assess the taxonomic features, as also suggested by Ronald and make your own judgement, as it's occurrence in Andaman-Nicobar sea would be extremely important. Do have a look at this asked for link:

Best

Syed

Thank you very much S. K. Paul

Thank you very much for answers.

 It cannot be "resting" or "regressing" gonads. Regressing phase continues for a relatively short time. I worked with such gonads and they look different: gonads are larger, with hyperemia; a large number of postovulatory follicles and atresial vitellogenic or hydrated oocytes in female; residual resorbing sperm in male.

This group of examined abnormal gonads includes male, female and sterile gonads that look very similar. Only histological analysis reveals gender or infertility.

Different types of abnormal gonads occur in walleye pollock: e.g. bisexual, with total atresia. And I try to describe ”new” type of abnormal gonads in this species.

We have GCMS

You can send the sample to me.

2J3KL northern cod though a fishery dependent index. Lots of good paper by Myers, Hutchings, Walters and others on it. You could argue that almost all assessment use poor indexes since we do not actually know if they are proportional to abundance. There are a few salmon cases where we actually know. I think the P. hake acoustic time series was thrown out due to poor ground-truthing but it would be tricky to connect the index in the assessment to the management decisions made. There are a number of issues with the indexes used in the tuna assessment due to standardization problems. Would also be difficult to make the connection between these and the management advice.

Dearest Ifra

hope this slide could help

ali

Hi Yu-Chun,

There are several interesting publications out there which deal with fisheries in the large Chinese lakes. For most of them you need to have an chinese access (which I do not have), but maybe you know someone who can help you getting those full texts:

Poyang:

Hu et al. (2005) - http://en.cnki.com.cn/Article_en/CJFDTOTAL-CJLY200505005.htm

Liang (2008) - http://en.cnki.com.cn/Article_en/CJFDTOTAL-QHDZ200805007.htm

Qian et al. (2002) - http://en.cnki.com.cn/Article_en/CJFDTOTAL-SSWX200206005.htm

Yang et al. (2011) - http://en.cnki.com.cn/Article_en/CJFDTotal-KXSD201101014.htm

Yu and Sun (2006) - http://en.cnki.com.cn/Article_en/CJFDTOTAL-ZYJJ200605010.htm

Zhang and Li (2007) - http://en.cnki.com.cn/Article_en/CJFDTOTAL-FLKX200704014.htm

Dongting:

Chen et al. (2004) - http://www.fao.org/docrep/007/ad525e/ad525e0c.htm - part of the FAo proceedings: Welcomme and Petr (2004) - http://www.fao.org/docrep/007/ad525e/ad525e00.htm#Contents

Chen et al. (2009) - http://link.springer.com/article/10.1007/s10641-009-9517-0

Lin et al. (2013) - http://ssswxb.ihb.ac.cn/EN/abstract/abstract20.shtml

Liu (2002) - http://en.cnki.com.cn/Article_en/CJFDTOTAL-XYYZ200208007.htm

Ru et al. (2008) - http://en.cnki.com.cn/Article_en/CJFDTOTAL-FLKX200801017.htm

And a bit more general, but still helpful - papers on the Yangtze lake fisheries:

Chen et al. (2009) - http://link.springer.com/article/10.1007/s10641-009-9517-0

Fang et al. (2006) - http://onlinelibrary.wiley.com/doi/10.1890/1540-9295(2006)004[0369:BCITLO]2.0.CO;2/full

Fu et al. (2003) - http://link.springer.com/article/10.1023/A:1023697714517

Guo and Li (2003) - http://www.sciencedirect.com/science/article/pii/S0044848603004782

Turvey et al. (2010) - http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2009.01395.x/full

I hope that will get you started.

All the best,

Michael

Hi John,

It's usually best to model the raw data, which in this case is stem weight with control/treatment as a covariate. It can also be easier to choose what distributional assumption you want to make about your error structure of the raw data. For example the error structure of weight will likely be best described as a log-normal distribution. On the other hand, what is the distribution of the error structure of a derived ratio between two log-normal distributed weights......not quite as clear.

Wish you well,

Dan

Thank you, Nichols, for your valuable suggestions and information. Yes, ASVCP recommends non-parametric methods but it requires sample size no less than 120 whereas, mine is between 90-100. It looks like robust technique would be preferable (especially in non-gaussian distributions) and for other cases, non-parametric bootstrap will serve the purpose. I'm using 'reference value advisor' MS excel plugin and it has all these options.

I definitely agree with the comments above. However, you may be able to use chemical actinometry under your flow conditions to validate any calculated irradiation dose. (reference attached)

Dear, friend

can follow this method for  fatty acid (One-step method for quantitative and qualitative analysis of fatty acids in marine animal samples by Sakdullah Abdulkadira, , , , Makoto Tsuchiyaa.  Journal of Experimental Marine Biology and Ecology, Volume 354, Issue 1, 4 January 2008, Pages 1–8.

I agree completely with Peter Howgate words. Perhaps he is the main living expert on TVBN in fish. But it is not a problem of authority and/or expertise. TVBN depends on a number of factors very difficult to handle in practice:

(i) On the methodology utilized (distillation methods yield in general higher values than diffusion methods, but it does not means that distillation methods give similar values).

(ii) Each fish specie has an "initial" TVBN (it is not zero). However, this initial TVBN° could change with the season (spawning influence) and capture method.

(iii) On the type of fish. White lean fish (like cod) and lean flat fish show the lowest TVBN°, fatty fish like sardines and tuna have higher initial values, and elasmobranch like rays and sharks usually have the highest.

(iv) In general each fish specie, during a given season (and for a capture method) has a TVBN dynamics. During a initial phase after capture TVBN° remains more or less constant, but after certain point (depending on the fish specie, but also on storage temperature and fish handling) star to increase exponentially.

(v) In theory regulatory limits provide for an allowance te decide between "spoiled" and "non spoiled" fresh fish (only fresh fish!). After the limits the regulator has assumed that the fish is spoiled and unfit for consumption as such in the EC.

(vi) In the very old literature it was the justification that after certain level of TVBN (say 50 mg) started (even in white lean fish) the production of non-volatile amines (like putrescin and cadaverin) that could be considered toxic. But I have not seen recent confirmation on that; and there is a long discussion about this, because without this justification the limits are based on quality reasons and not on safety reasons.

I do not think this is a type of regulation that will change any soon. TVBN assay it is relatively easy and inexpensive to perform, all fish technologists know about it (at a certain time it was said that you could not consider a fish technologist without publishing a TVBN paper at international level - I did). I think that all serious fish technologists know about the problems with TVBN, but a method to suit regulators in the EU has not been found yet.

My best advice is that you have to search and know about your fish TVBN dynamics and TVBN° to identify conditions and seasons for your fish to be exported to the EU.     

The answer by David nicely illustrates the most importants points in doing this type of work.

One more remark: in using this approach, you assume that the digestibility of the basal diet does not change regardless of the ingredient  and its amount added to that basal diet. Also you assume that digestion goes on more or less undisturbed.

 This is certainly not always true. We have seen that fat containing ingredients might easily cause problems in the digestive process making the results sometimes hard to interpret.

Hello Irwan Sofia

please check the resources

Thank you Nirmala. 

Here is another reference that contains a review of literature assessing length of first sexual maturity.

Aquaculture of Grey Mullets (International Biological Programme Synthesis Series 26)Sep 30, 1981

by O. H. Oren

 You need to reduce the feed intake by administering less amount of feed and also avoid feeding when the temperature is highest. Because fishes are poikilotherms they  are more active with rising temperature but at a point they are unable to metabolize the feed eating, usually characterized by presence of enlarged biles. This is a clear indication of indigestion.  If your fishes are reared in the open (outdoor facility) if the facility is  not that big, perhaps you can provide a some shade to reduce the direct impart of the sun on them.

thank you all for your answers. our fish are weaning normal now. Apparently they like higher density 

Seems not available

Okay... I will make some graphs and send them to you :)...

Hi Sileesh

Yes, using kernel density estimation is advisable when you analyze length frequency distributions (or any other type of frequency distributions) because it allows you to quickly explore and to characterise the distribution of your dataset. Two issues that should considered with this approach: a) type of kernel to be used (there is a bunch of them, i.e. Gaussian, tricube, triweight), b) Bandwith selection. I will just focus on the bandwith issue. See an example in the attached figure. I used R to create a toy dataset for a random variable with a tri-modal distribution (n = 3000 observations), that is simply the combination of three random variables with normal distribution with mean 0, 3 and 6, respectively, and SD=1 in all cases. 

When your bandwith is too high (bw = 2 or 1), the resulting frequency distribution showed by the kernels indicate a rather unimodal normal distribution. The tri-modal distribution becomes apparent only when you decrease the bandwith. Of course decreasing the bandwith too much increases the noise. I know there are some approaches to estimate the optimal bandwith, but honestly I am not familiar with them. Said that, if you are only interested in exploring length distribution data, kernel density estimation may be very useful technique in help you identifying the presence of multiple size cohorts (or the lack of them). 

Good luck with your research

I don't think you can extract the chitin whic is insoluble in any known organic solvents. Normally alkaine-washings at boiling water bath resulting in partial N-deacetyaltion and solublization in water.  There is no such method reported as the easiest or fastest way!!

Thanks!!!

Venancio

Dear Mohammad!

C and WP are the seasonal parameteres of this growth function. 

C is the amplitude of seasonal growth oscillation and WP  is the Winter point

In the attached pdf you can find a description of these parameters and the calculation method of them.

Best wishes: Zoli

I agree with you. 

Feed comprises the largest production cost for aquaculture industries in which it is extremely high, being up to 70% of the total cost. For this reason, the research for alternatives to fish meal is one of the first international research priorities. Soybean meal and other plant protein induces enteritis in the distal intestine of Atlantic salmon and rainbow trout. When producing organic feed and fish, these substances must be investigated effects on the fish intestine and liver inflammation.

Your welcome sir. I've just sent the photos here.

There is a reference in poultry. However, the practice is discouraged because of the chances of contamination from heavy metal and other toxic substance. 

http://nectar.northampton.ac.uk/5238/3/Paul20135238.pdf 

The answer to your question depends on quite many factors. You'd find the info need in the  FAO Fishing Manual:  Fishing with Light, (FAO, Rome).

I'm agree with Gideon Khoo.

Yes, Fish aggregating Device is one method of studying fish assemblages without fishing. This is in use off some tropical Islands in the Arabian sea.

Yes, there many marine fish species eat anchovy, as sardinella aurita , scomber japonicus, Etrumeus teres. this in egypt, you can read the paper food and feeding habits of roundherring etrumeus teres in the egyptian mediterranean sea,  by Alaa Osman and Mahmoud Farrag, els

I also found 5 articles about this subject.

Best wishes for a successful study.

Hi Mohamed, apart from the suggested literature, I think I could assist you, if you'd ask more specific questions.  MB-Y

I think that Christopher is right, though his explanation can be simplified.

The position of the centre of the ellipse can be estimated as the arithmetic means of the start and end latitudes and longitudes. While that is an approximation, for the short distances of trawl tows, even ones that extend over several hours, it should be fully adequate on any real-world trawling grounds. (It wouldn't be if someone trawled under ice at the Pole!)

Contrary to Christopher's explanation, but in agreement with his result, the length of the longer radius is necessarily one half the length of the vessel's path. Imagine a trawler heading from the tow's start point directly away from its end point, then reversing course and heading direct to that end point. The turn point must be (as  Christopher said) [dt-dp]/2 from the start point. Imagine that, instead, the trawler steamed straight past the end point, then reversed course. The turn point would then be the same [dt-dp]/2 beyond the end point. Hence, twice the longer radius is dp+2[dt-dp]/2, which is simply dt. Hence, the radius is necessarily dt/2.

I agree with Christopher on the use of Pythagoras to get the minor radius.

That gives all of the information needed to define the ellipse, though you then face two greater challenges: (1) projecting that ellipse onto a lat/long coordinate system, rather than one oriented around the line between the start and end points, and (2) projecting the result onto some map projection -- probably, but not necessarily, Mercator. I'd recommend looking for GIS software that would do those steps for you as they might get labour intensive.

And, just to state the obvious so that skeptics don't suppose we have forgotten it: The ellipse will be larger than the extent of all possible real tracks because vessels that are towing gear cannot reverse course instantaneously. Requiring radiused turns, and given the fixed length of the vessel's track, would bring the furthest point on that track closer to the straight line between the start and end points. In a different sense, the ellipse might be too large because some of the area within it could be unfishable. (Consider, for example, a case of start and end points lying either side of an island or perhaps a closed area, patch of hard bottom or whatever.)

Dear Sasha - unfortunately I am not aware of online catalogues. But I have included a pdf. that might be of interest. Best wishes, Jorgen

Dear colleague, You may be interested in the immunomodulating effects of antibiotics, which are allowed for use in aquaculture. Amazingling enough the antibiotic, oxytetracycline, is still approved, but highly immunosuppressive both in fish and mammals. See also 2 added papers. With my regards, Willem

Thanks Justin y gracias Gustavo!

Please read this. 

and this