I think it depends on the species and habitat being surveyed. While for most marine fishes survey impacts are likely to be minimal, for many freshwater systems and some marine habitats there could be impacts. Several journals e.g. J. Fish Biology require these issues to be taken into account before results from a study will be accepted. There have been several editorials in the journal which discuss the ethics of studies on fish. Furthermore in the UK experiments on fish, including internal tagging and some forms of external tagging, are covered by legislation which requires the researcher and the study to be licensed by the Home Office. The application process for a personal and project license is quite involved and requires attendance at training course as well as consideration of the numbers of animals which will be affected balanced against the number needed for statistically robust results.

Scientific sampling on vulnerable marine habitats is also covered by an OSPAR Code of Conduct although this is voluntary rather than mandatory.

The whole issue has become very political in some specific instances involving other marine organisms e.g. the Japanese 'scientific' whaling program which many regard simply as an excuse to keep the whaling fleet going.

It has been assessed by scientists that almost 50% of a fish population is consumed by various predators including natural mortality in their ecosystem & humans target the rest. The numbers being so big,I don't think sampling a variety will effect its population to any extent,unless any of them are in the vulnerable category.

I agree to this answer.

Compared with other factors (environmental or anthropogenic), the influence of scientific sampling/observations is relatievly low (unless you sample on small scale endemic species for example or on heavily overexploitet stocks).

As it is in fisheries-survey, you often even want to imitate the effects and the influence of fisheries for standarized measurements, thinking of gaining cpue, survival-rates, catchability-studies and so on.

Of course, the impact should always be orientated on what you want to achieve and be as small as possible, catching and killing hundreds of tons of fishes where maybe one or two tons would have lead to the same results is irresponsible.

Hello all,

I often think about this issue. However, I believe that it is difficult to have a clear assessment, since there is a paradox to resolve. That is, in order to assess the effect of sampling you need to sample! Imagine that you are comparing a reach (or river) that has been studied and sampled for some time with another (control) river that has not been sampled at all. We cannot draw any conclusions on this hypothetical study, since we have no previous information regarding the control river, which by definition should not have been sampled. We don't know if the two differ because of the sampling or other natural factors.

Do you see my point?

Stefano

In the U.S., the environmental effects of all federal actions (including those funded by federal agencies) are required to be examined pursuant to the National Environmental Policy Act. As a result, the effects of scientific sampling conducted or funded by federal agencies are supposedly examined in one of three types of documents (Categorical Exclusion memos, Environmental Assessments, or Environmental Impact Statements). However, the quality, consistency, and compliance with these requirements vary among the completed documents. The Magnuson-Stevens Fishery Conservation and Management Act also requires scientists conducting studies in the U.S. EEZ to obtain a Scientific Permit that includes providing information on the impacts of the studies. Further, the Endangered Species Act and Marine Mammal Protection Act require assessments of activities that might affect threatened, endangered, and depleted species. Information on the impacts of scientific studies on species covered by these statutes are contained within the requests for permits or ESA consultations. Again, the quality, rigor, and consistency varies among the products produced.

Here you cona find a good discussion about that topic. Heupel & Simpfendorfer. 2010. Science or Slaughter: Need for Lethal Sampling of Sharks. Conservation Biology, Volume 24, No. 5, 1212–1218.

Thanks to all for your interesting answers.

If it's sea fish, there are research vessels that undertake small scale fishing activity for sampling purposes - their fishing is accounted for as part of the EU's assessment of safe fishing limits, so they don't add to the impact on marine life.

I think it depends on the species and habitat being surveyed. While for most marine fishes survey impacts are likely to be minimal, for many freshwater systems and some marine habitats there could be impacts. Several journals e.g. J. Fish Biology require these issues to be taken into account before results from a study will be accepted. There have been several editorials in the journal which discuss the ethics of studies on fish. Furthermore in the UK experiments on fish, including internal tagging and some forms of external tagging, are covered by legislation which requires the researcher and the study to be licensed by the Home Office. The application process for a personal and project license is quite involved and requires attendance at training course as well as consideration of the numbers of animals which will be affected balanced against the number needed for statistically robust results.

Scientific sampling on vulnerable marine habitats is also covered by an OSPAR Code of Conduct although this is voluntary rather than mandatory.

The whole issue has become very political in some specific instances involving other marine organisms e.g. the Japanese 'scientific' whaling program which many regard simply as an excuse to keep the whaling fleet going.

It is a very productive and very meaningful discussion. I think, high fecund fishes will be less prone to demolish. but still there are many biological, environmental and very importantly overfishing by fishermen, which draws more attention for fish biologist, fisheries managers. Inland aquatic system like river, reservoirs, lakes are more susceptible environments which put the fishes at under threat. while experimental sampling we have to release threatened fishes to same system after we take picture and other measurements. This may save some of the fishes. but we need to calculate the loss occurred due to experimental sampling.

Sample for any scientific study needs very limited quantity (numbers/biomass). Nevertheless, it depends on the types of study to be undertaken. If an exploratory fishery survey is needed, you need to quantify the stock of a variety of species which has its own impact if you do frequently with unsuited gears. So proper time interval to be fixed, once in five or ten years and sampling to be done with proper gears. In case, you wanted to study a particular single species, selection of net mesh size permitted to be used which will prevent the loss of other species. For scientific purpose,biological sampling is permitted every where and it may not have much negative impacts if you plan carefully. In the case of estimating the quantity of a species caught for scientific purpose, the data collected may be statistically treated along with the data estimating fishing mortality. Additional care should be taken in the case of critical/threatened/endangered/over exploited species.

Scientific sampling does not always require to kill specimens. Diversity and abundances of coral reef fishes are often obtained visually by divers (see http://www.spc.int/DigitalLibrary/Doc/FAME/Manuals/Labrosse_02_UVC.pdf for ex.) or through video cameras (http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0084344 for ex.).

Unfortunately, visual observations give you access to a part of the full richness of these habitats.

I agree all of you, but my question is more focused on fisheries assessment trawl surveys. For example, we carry out an assessment trawl survey in Flemish Cap (Terranova, Canada) since 1988. In 1992 this area was closed to fishing, but scientific surveys still continue to assess the stock dynamic of demersal community. Sometimes we have caught tonnes of fish (even juveniles when the tow went through a fish school). Currently the area is open again to fishing, so I'm sure scientific surveys have not impacted notably communities, but, even so, I would like to quantify that impact. Maybe, scientific assessment catches (even when they are "small") should be incorporated in general fisheries statistics... or not.

Hello,

Check out these papers and related research, it might provide some info that you're after:

Januchowski-Hartley, F.A., Graham, N.A.J., Feary, D.A., Morove, T. & Cinner,

J.E. (2011). Fear of fishers: human predation explains behavioral changes in

coral reef fishes. PLoS ONE, 6, e22761.

Fraser A. Januchowski-Hartley, Kirsty L Nash, Rebecca J. Lawton (2012) Influence of spear guns, dive gear and observers on estimating fish flight initiation distance on coral reefs. Marine Ecology Progress Series. 469:113-119.

Best,

Even

I understand sampling independence as a concept, not a goal, we always try but it is surely impossible, but at least we must assume and understand the sources of methodological error in order to discuss them

Very interesting discussion, and timely for me too. I agree that the impact of sampling depends on the population characteristics of the fish being sampled, as well as the study design. It may also be possible to detect what might be negative impacts of your study on a fish population during the life of the project.

While non-destructive sampling can be used to answer some question, destructive sampling cannot always be avoided. I also suspect that even non-destructive sampling impacts fish populations, e.g., fish can become shy, and they can learn how to avoid sampling gears. We change the very thing we try to measure, simply by trying to measure it

Dear Sarah, Thanks for the publication

I have some experience to share, take a look

https://www.researchgate.net/publication/261649299_THE_EFFECT_OFARTIFICIAL_REEF_STRUCTURAL_COMPLEXITY_AND_BENTHIC_COLONIZATION_ON_GILL_NET_FISH_ASSEMBLAGES?ev=prf_pub

Article The effect of artificial reef structural complexity and bent...

Here seems to be some confusion between scientific sampling (1), and exploratory or survey fishing (2). (1) is sampling commercial catches, normally performed by scientists or scientific technicians sailing on board vessels fishing with commercial gear, who're taking off the catch representative samples to be examined either on board, or in labs on land. (2), sometimes called control fishing (trawling, seining, etc.) is usually performed using commercial fishing gear, either in periods and/or areas where commercial fishing was stopped, or along with commercial fishing fleets, sometimes using different gear, for example with smaller mesh, to catch all sizes of the target spp. + accompanying spp. The catches, after examination etc., are landed for market, and should be included in the general statistics.

In both cases, I don't think there's a worrying significance, certainly not in the case (1) and only a certain increase in the total effort in case (2) MB-Y