Bottle-Nosed Dolphin - Science topic

Pickle jar....metal lids may have sound transmission properties than plastic. I have used PVC plumbing for underwater applications....they come in lots of diameters; cut what length you need and you can glue on the end caps that are sold to match the pipes. There is permanent glue sold in plumbing supply shops specifically designed to contain water in pipes....and for removable you can skip the PVC glue and use a bead of silicone glue applied on the exterior joint so you can peel it off to remove.

Its hard to answer this question without knowing details of the whole setup. It may be that the sound card you are using has a bandwidth limitation. You could try using different recording software with the same hardware or switch to another laptop with a different sound card and see what changes. The info at http://www.cetaceanresearch.com/hydrophones/c54xr-hydrophone/index.html suggests the hydrophone & preamp should be OK. (Read the specs on the sound card you are using.) . You could always call Cetacean Research and ask what you are doing wrong.

There are two more papers dealing with Stenella sounds, even though not S. attenuate:

Herzing, D. L. (2014). "Clicks, whistles and pulses: Passive and active signal use in dolphin communication." Acta Astronautica 105(2): 534-537              

Lammers, M. O., et al. (2003). "The broadband social acoustic signaling behavior of spinner and spotted dolphins." J Acoust Soc Am 114(3): 1629.

Dear Martin,

There are a number of things that determine the insulation of blubber, thickness is definitely one of them, however fat/water content is equally important. There has been a study in pinnipeds which might give you some more information on this.

I hope this helps.

Best wishes,

Tessa

Since you don't have photos, it's difficult to know what the cause of the condition you mention. However, the video and photo from Simon seems to me to be stalked barnacles. They have been described in many cetaceans, and I've found in franciscanas (Pontoporia blainvillei) from my area. You can see a photo of it at https://flic.kr/p/rPR6qt

To me it looks like the animal was injured by some type of fishing gear.  Sam Ridgway

Hi Bruno, no doubt about it. This individual presents the remains of a propeller strike of at least two years old (the scar is not longer whitish). I have seen these wounds quite frequently in Chilean Patagonia with the increasingly busy fjords due to the salmon farm expansion. I have several photos just like this one but mainly on L. australis. Despite the photo is not very big, you can see at least four contact points all separated by the same distance. Your photo is great since it almost replicates the position the dolphin had a second before the collision happened. The cuts are at the same distance but the two biggest are also at the same depth. They are not in straight lines but slightly curved both in the same manner regardless of the amount of mass involved (active source).

In contrast, in my experience net wounds tend to be located at the closest section to the flukes and frequently they include longitudinal cuts on the flukes themselves. The net slides back since the peduncle gets thinner towards the tail but then can get stuck on the tail producing the cuts at that level. The lesions of this individual are not grouped close to the tail but positioned at same distance from each other regardless of the thickness of the peduncle. Also the cuts from the surface (dorsum) present a forward direction. They are not even vertical but towards the front of the individual. Whatever did these cuts, had "its own energy" in order to achieve that direction and the high speed needed as well to counterfeit the movement of the dolphin. Anybody with experience performing necropsies on cetaceans can confirm how hard is to cut at this level of the body. The tissue is very dense. These lesions are not due to a passive source. Nets tend to produce only a superficial damage unless getting stuck on structures like flippers or the tail due to their dragging effect. Therefore the cuts, when due to nets, tend to cut towards the back of the affected individual.

In conclusion, considering the direction of the wounds, their period, number and slight curved shape, we have no nets here but the "classic" small propeller blade wounds in perhaps the most frequent site where dolphins get these lesions. I am always surprised how some individuals can survive and keep up with these wounds but at the same time we do not know the rate of mortality. Perhaps these cases of survival are only a small percentage. We simply do not know.

It is important to report these collision cases to IWC and IMO since there is a worldwide database collecting information about this threat to both wildlife and vessels. Speed and/or path restrictions can be implemented in areas with high rates of collisions. Governments are required to report these cases to IMO but the details of this procedure depend on each country.

I recommend you to check some of the pics we posted in this paper:

kind regards

Hi Hannah. Do not forget that mostly you are talking about a coastat species, and that interactions of the species with artisanal fisheries and fishing gears like trammel and gill nets are quite strong in most of the areas studied so far. So I will begin with the spatial description of the fisheries in terms of fishing grounds, its vulnerarbility for bottlenosed dolphins attacks, target species both for fisheries and as food for the dolphins, and finally distribution and abundance of dolphins in the area where the MPA is suposed to be declared. This will give you an insight of the potential future conflicts with fishermen and guidelines for the zoning of the MPA. These two aspects working together are a critical point in the future failure or success of the MPA to come. Yours,

Pep