Under Javier's watch

Good weather and fair going, not too much rolling, more sun than rain, the little birdies flying about and the turtle dove gone missing. Photographing the birdies has proven complicated and the task has been dropped. We are all very busy. The deckhands have installed the extra tables we need for our sampling and have been working on the gear warps. The black gang has installed extra ligths above the sampling tables, and we biologists had our usual meeting to go over the sampling protocols and distribute work. All the material has been distributed in the wet lab. Be patient, we will show you all this in due time!

Making the warps ready

Camera, lights and...

 

It is not easy to organise a survey like this. We will have no shops anywhere close and we must be sure we won’t miss anything. Thus, the material is packed in crates weeks before departure. The list takes 8 A4 sheets without margins and in small font. To give you an idea, the 18th of May 30 crates plus a further 30 bulky packages (weights, barrels, baskets, ictiometers, trays, cardboard boxes,...) were taken on board. The crates hold anything from spare parts for the weights to usb connectors, laptops, helmets, calipers, pens, markers, plastic bags, rubber gloves, guidebooks for fish, invertebrates, cetaceans, birds (must look up those birdies), anti-rust spray, pocket knives, and a long etcetera.

All this hassle is needed to try to ensure that the fish ending on your china is sustainably caught. The survey is the first step of a long process involving tens of professionals, starting with the 35 people on board R.V. Vizconde de Eza. We have talked about this before but we will explain it again for the new readers.

Our main goal is to gather information on the demography of fish populations of commercial interest. We need to know the proportion of juvenile and sexually mature fish, males and females, if they are spawning or have done it already, their size, their weight, their age. We obtain this information from the samples we get from what we call standardized hauls. They are all the same, take 30 minutes with the ship at 3 knots. Takin all the hauls in the same way allows us to compare the catch among them, i.e. estimating catch per swept area, and more importantly, compare different surveys.

We plan the fishing in advance. Our study area is divided into strata at different depths, and depending on the area of each stratum we need to take more or less hauls from it. Depth is a good factor to split our study area, since different fish species prefer living at different depth ranges.

After each haul we separate all the catch by species. Then, from each species we have to measure, weight and open many individuals to obtain all the data we need. We will show you all this over the next days with photos and some videos.

 Besides, invertebrates are also identified, photographed and weighted, and a CTD data logger is used to compile information on temperature and salinity of the water all the way from the surface to the bottom. You will see the CTD as well next week.

The CTD data are sent to the IEO branch in Madrid at the end of the surveys, and they are stored in an international database where they are accessible to all people or institutions requiring them.

The fish and invertebrate data go to the IEO databases, where researchers can access them for different purposes. One of them is the evaluation of marine resources. Our colleagues Diana and Fernando spend several weeks a year in Canada, representing Spain in international scientific meetings where all countries involved pool their fisheries and survey data to estimate how much marketable fish is there in their study area and how much can be caugth without endangering the populations. This is what we call the scientific advice. The final decission rests on the managers’ hands, but more and more often the scientific advice is adopted. Next step is to split the quotas among countries and send the fleets fishing.

So off you go, have some nice fish tomorrow for lunch and make sure you finish it all!