Interesting question about our ability to objectively quantify fish schools, potentially, from space. I have no experience with this technology, but will be interested if anyone responds in the positive to your question.

Interesting question.

Fishes tend to aggregate for feeding for sure, but obviously it depends on the species (small pelagics maybe are the most likely to follow dynamic features in ocean as they feed almost at the basic levels of the food chain,). Other fishes, for example demersal or benthic species, it is probable that just don't care of what is happening at the surface.

On the other side, it is likely that physical parameters related to ocean features (temperature gradients at fronts for instance) can act in regulating swimming paths and or areas of aggregation of fishes, because they probably look for places where they can found optimal temperatures (from a metabolic point of view for example).

Other speculations can be made on all the phases of the life cycle of a fish (reproduction, feeding, spawning etc etc)

Let me know your feedback, as I'm interested too to this topic.

Regarding the presence/absence of fish aggregations, depending on the species you are interested in a passive acoustics approach might prove relatively cost effective. The following papers might be of interest:

- Luczkovich, J. J., Mann, D. A., & Rountree, R. A. (2008). Passive acoustics as a tool in fisheries science. Transactions of the American Fisheries Society, 137(2), 533-541.

- Van Parijs, S. M., Clark, C. W., Sousa-Lima, R. S., Parks, S. E., Rankin, S., Risch, D., & van Opzeeland, I. (2009). Management and research applications of real-time and archival passive acoustic sensors over varying temporal and spatial scales. Marine Ecology Progress Series, 395, 21-36.

- Rowell, T. J., Schärer, M. T., Appeldoorn, R. S., Nemeth, M. I., Mann, D. A., & Rivera, J. A. (2012). Sound production as an indicator of red hind density at a spawning aggregation. Marine Ecology Progress Series, 462, 241-250.

- Gannon, D. P., & Gannon, J. G. (2010). Assessing trends in the density of Atlantic croaker (Micropogonias undulatus): a comparison of passive acoustic and trawl methods. Fishery Bulletin, 108(1), 106-116.

- Hernandez, K. M., Risch, D., Cholewiak, D. M., Dean, M. J., Hatch, L. T., Hoffman, W. S., ... & Van Parijs, S. M. (2013). Acoustic monitoring of Atlantic cod (Gadus morhua) in Massachusetts Bay: implications for management and conservation. ICES Journal of Marine Science: Journal du Conseil.

Fish tend to aggregate for feeding, reproduction (spawning areas), courtship, spawning areas, social recognition, etc.. The species tends to change their conductuctas when this particular event, such as courtship

Fish tend to aggregate for feeding, reproduction (spawning areas), courtship, spawning areas, social recognition, etc.. The species tends to change their conductuctas when this particular event, such as courtship. In the ocean there are important events which shaped fish eficienteme advantage such as currents, eddies, etc.., In which efficient producien food chains

Can potential fish school presence in the Baltic Sea be predicted by remotely sensing certain physical (SST) and biological (Chl) "indicators"?

Yes, It is possible. We need to considerated the that at certain scales climatic and Physical factors affect profoundly the distributions of the species, this has been know for a very long time. In the last two decades mathematical techniques designed to estimate the geographic extent of the fundamental ecological niche, or subsets of it, defined mostly in coarse-scale climatic dimensions or climatic niche have seen increasing use.

In this specific case you can reconstruct the school niche by relating data on schools ocurrence with data combinations of enviromental variables most closely associated with observed presence, you will asume in this case that the SST and Chl are this combination. After that assumption you can use diverse algorithms like range rules, multiple regression and other generalized linear and additive models to make the prediction. After that, you will obtenied the model and you can use a exponential or linear model to predict the distribution of the schools in the next 50 or 100 years.

How reliable would such an approach be?

The reliability of the model depends basically in the biological basis of niche modeling. In other way, is very important tthe quantity and quality of the occurrence data. Also the type of model used is very important, but generally many model have been improved very succesfully in the past.

Dear Dr. Victor

SST, Sea Surface Heights, Sea Surface Chl and vertical temperature profiles (Satellite and Argo data) are being used to probe fish aggregates in some areas in the Indian Ocean region to demarcate the sites as potential fishing zones. There are systems (radio) to convey the information to the fishers as well. Following are some literature.

http://www.eorc.jaxa.jp/eSA/protoact/completed/sri-lanka_2010jun.html

http://www.incois.gov.in/Incois/marine_fisheries_main.jsp

http://etd.lib.metu.edu.tr/upload/12606160/index.pdf

http://140.121.160.124/sm/961_2/%E8%AC%9D%E4%BD%B3%E6%A8%BA.pdf

http://nopr.niscair.res.in/bitstream/123456789/1577/1/IJMS%2034(4)%20430-440.pdf

Provide areas of aggregation fish schools, or the presence of the same, in particular areas and at particular times, is an information due to the variety of biotic and abiotic factors that affect, it may be possible through a historical analysis of the data. The problem, in my humble opinion, and understand if there are data and how to retrieve them. who might have information of this type may be sure the local fishermen. then the Interveste or complete logbook fishing days with information about the area fished, the species caught, landed and the quantities of waste, it might be a good starting point. I attended a job (project Mars + of gender and the amount of data that one gets is remarkable. otherwise, but this is a hypothesis-fetched, you could try with techniques similar to those of remote sensing, and then take advantage of the different response of wavelength of the various species. but the technical difficulties are numerous, as it comes to water, and then one should consider the deviation of the light, the depth, etc. etc.. know with certainty that there are algorithms that are applied to the correction of satellite images , but I still have little experience in this regard, I just started to work on the management of fishery resources. however, are interested in the subject and its development using SST.

Usually fish tend to aggregate near the waters which are rich in the food . Mostly all fishes will form schools while breeding , feeding , near the spawning grounds , Nursery grounds so they may aggregate near oceanic fronts, river flumes and also. in mangroves as they provide food and also protection from predators.The food Starts with primary Producers, primary consumers and ends with tertiary consumers.So if we know the food and feeding habits we can easily predict the fish, We can Find the Primary Producers with SST and Chl as the biological indicators so with them we can find the fish aggregates (Schools) Easily !Fish potential can be predicted by the SST and Chl biological indicators & its a reliable approach in predicting the fishing potential in the oceans Avoiding over exploitation.

Quite a number of things can affect the aggregation of fish and these include both physical parameters such as temperature and turbidity. While the chemical parameters such as level of dissolved oxygen, ammonia and pollution with other chemical substances in the water can also affect their aggregation. Moreover, the biological processes/ life cycle of the fish can as well affect the aggregation of fish

Vic,

As you've assuredly tapped the remote sensing literature on the Baltic,

you might consider looking at what has been done on the specific species in

other areas. To follow through, I did a cursory google search.

Two sources on Baltic fisheries:

http://www.helcom.fi/environment2/biodiv/fish/en_GB/history/

http://oceana.org/en/eu/media-reports/publications/fisheries-management-in-the-baltic-sea-how-to-get-on-track-to-a-sustainable-future-in-baltic-fishe

I know that sardines come from the Baltic (they are in our local stores)

there is a paper from the Aegean

http://www.academia.edu/1157958/Habitat_discrimination_of_juvenile_sardines_in_the_Aegean_Sea_using_remote_sensing_environmental_data

Obviously, any references to Mike Laurs "old" CZCS Tuna study off California

would point to more articles.

Regards.

--rick

In the Joint Research Centre there is an ongoing project led by Jean Noel Druon aiming to identify the habitat of key marine species, such as bluefin tuna, fin whale and hake, using satellite-derived data of the sea surface in support of fisheries management and control and/or species protection. Check this website for more information: https://fishreg.jrc.ec.europa.eu/fish-habitat

In this site you will also find links to related papers.

The developed models for bluefin tuna in the Mediterranean are fully operational and JRC provides short-term predictions of feeding and spawning habitats. These predictions are used by national and EU authorities complementary to other information such as VMS data, to control the tuna fishery.