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Delta Del Llobregat

Home Forums Field Trips & Conservation Delta Del Llobregat

Viewing 15 posts - 121 through 135 (of 152 total)
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  • #348013

    Matt
    Keymaster

    Park paid for it Colin. 🙂

    Jim, not entirely sure lol. We definitely want to get some huge air pumps and we sort of discussed building a covered area with some aquaria inside, but let’s see…at least now we have more options.

    #313636

    Matt
    Keymaster

    Last weekend we went to check the pools, release some fish at the new site, check on the larger natural site where we released fish in March and build a couple of new artificial pools for production of live foods.

    Releasing fish at the new site:

     

    Web-1.JPGWeb-2.JPG

     http://www.youtube.com/watch?v=beU3yCnpmLM

    #313633

    Matt
    Keymaster

    At Playa de Ca L’Arana, where we released a load of fish in March. Unfortunately we weren’t allowed to fish due to nesting birds so saw nothing, but we’ll be back in a few weeks.

    Web-3.JPGWeb-4.JPG

    #313519

    Matt
    Keymaster

    At the breeding pools. One of the small pools has been destroyed by wind and there were several moorish geckos holed up among the wreckage, one of which was shedding skin and also has what appears to be some kind of parasite (mites?).

    The Aphanius in the main pools were looking brilliant and spawning all over the place. We also noticed that younger/subdominant males were using the pool walls as spawning sites.Web-6.JPGWeb-7.JPGWeb-8.JPGWeb-9.JPGWeb-010.JPGWeb-011.JPGWeb-012.JPG

    #313828

    Matt
    Keymaster

    …a video of the fish in the pools taken on Roberto’s phone.:smile:

    http://www.youtube.com/watch?v=SxtSbWsmp58

    #313827

    Graham Ramsay
    Participant

    The fish seem very visible against the light bottom Matt. What sort of predation is going on, if any?

    #313365

    Matt
    Keymaster

    None or minimal as far as we can make out but unsure to be honest. That light part is very shallow and they only go there to spawn, plus A. iberus has very few natural predators. I guess some fry will be getting munched by the abundant dragon fly nymphs?

    One of the main limitations of the project is that we both work full time, and Roberto has a a young family, so we can’t spend as much time as we’d like at the site. The park can’t afford another member of staff to help out, so until more money is available we’re a bit stuck in terms of working out exactly what’s going on the pools.:?

    #313364

    Plaamoo
    Participant

    It’s surprising that there’s not a flock of gulls or a cormorant or kingfisher hanging around gorging themselves. Easy pickings!

    #313127

    Matt
    Keymaster

    Think they’re a bit small for cormorants and never seen a kingfisher in the Llobregat delta Jim, maybe a little too urbane and coastal for them?

    There are gulls but they’re much commoner around the city rubbish tips and in the centre. I’ve not seen a single bird species at the site that might prey on Aphanius. Also, the fish might look pretty relaxed there but trust me they can disappear and not be found in an instant – we had to sneak up and wait a while, or view them from distance, to see them at the surface like that. 

    Much more worried about Procambarus clarkii getting into the pools than any bird.:?

    #313539

    Graham Ramsay
    Participant

    No egrets?

    #313540

    Plaamoo
    Participant

    It would take a bunch to fill a cormorants’ belly. Not likely to bother unless they were having trouble. There must be gulls, terns? Don’t know about the common kingfisher population there but looks like it’s within their range. Coastal & urbane shouldn’t be issues. I had them coming into my patio and stealing the fish from my tanks in Thailand. Can’t remember which sp. With the numbers your ponds are producing it’s obviously not an issue.

    #313140

    Matt
    Keymaster

    Terns and egrets both occur in the delta but never seen them bother with our pools when less-exposed, more favourable habitat with loads of vegetative cover, not to mention thousands of Gambusia, is available very close by. Guess the odd bird could take a few Aphanius but like Jim said with the number we have right now it’s not a problem.

    That said there are a number of worrying aspects to this project, and personally I think things could be done in a more scientific way; a combination of politics plus lack of human resources and funding putting paid to that for now. I do voice concerns but ultimately have only a limited degree of influence into what actually happens.

    One important point is that some existing habitats of A. iberus are smaller than either one of our pools, but are fed by aquifiers whereas our systems are closed, another cause of trepidation as we’ve never yet performed a water change, cleaning procedure, or fed the fish artifically.

    Question is, do we need to undertake maintenance or should we trust nature to reach a balance? The latter is certainly tempting as the Aphanius thus develop under conditions of semi-liberty, and as things stand we’ve experienced few problems in terms of number of fish produced…

    #313117

    Plaamoo
    Participant

    I’d say keep it as natural ad possible. Especially since it seems to be working that way without much effort. Hatcheries and their practices are subject of great debate in my part of the country. Much of the debate is the effect that hatchery fish have on wild populations. Hatchery fish are known to be inferior and detrimental to wild populations, but to what degree? Being raised in a protected hatchery environment  deprives them of the trials and tribulations of natural selection and the end result is a lot of stupid fish! One specific problem is that rather than learning to naturally forage for food, they’re fed by scattering pellets on the surface. When the smolt are released they continue to look for food at the surface where they are easy prey for birds.

    #313103

    Matt
    Keymaster

    Yeah, one of the reasons we’ve not been feeding artificially so far is to encourage them to forage naturally, good to hear someone agrees!

    The University of Cordobá have been largely failing in attempts to breed Aphanius baeticus despite thousands spent on water treatment, UV units, and other equipment. Maybe sometimes we try to control too much?

    Edit – that said some of the fish we released last year could perhaps have been in better condition, and food did seem the limiting factor.:?

    #348288

    Matt
    Keymaster

    We’ve just been informed that our funding has been withdrawn due to the financial crisis. Looks like the project is a goner. More to follow once I know more, but it’s not looking good.:cry:

Viewing 15 posts - 121 through 135 (of 152 total)

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