Whale # 1 stomach content analysis

[Steve O'Shea]

The most recently stranded whale was in a very sad state, with quite a number of the teeth in the lower jaw badly broken

I refer this specimen to 'Whale # 1" in this separate topic; the next topic will be Whale # 2, then 3 and so on; within each separate topic I'll cite the species of squid (as identified from beaks), and the numbers of each beak-type recovered.

I've only just completed identification of the squid beaks within the stomach of Whale # 1. As far as I know (to the best of my efforts), every squid beak in the stomach was retained (despite this, the number of upper and lower beaks invariably differs).

If you like you can look at the squid (and in subsequent whales, octopus also) composition and try and make some sense out of the jigsaw (based on what we know of the New Zealand and adjacent water mass squid faunas). I've not provided lower rostral lengths for the beaks, as I've yet to measure them. Also, my camera is at home; pics of the beaks will have to follow another day.

Identifications are based on lower beaks.

Here goes:
Whale # 1, male, ~ 15m length, stranded 8/9 December 2004
Number of upper beaks: 54
Number of lower beaks: 31

Lower beak-determined squid composition in diet of Sperm Whale # 1
Architeuthis dux: 7 (7 upper and 7 lower beaks in sample; beaks fresh)
Mesonychoteuthis hamiltoni: 26 (26 lower and 29 upper beaks in sample; large beaks blackened)
Taningia danae: 7 (7 lower beaks; indet upper)
Mastigoteuthis sp. [giant]: 1 (massive lower beak; no upper beak)

I'll say no more, but much could be said.

 

[Phil]

Steve,

Apologies to bombard you with a couple of questions, but after having seen the tentacle club of a Messie last week, there are a few questions I'd kindly like to ask.

How do the Mesonychoteuthis beaks you have recovered in this, and other, sperm whales compare to the intact specimen you examined recently in size? Are the whales catching older more mature specimens on average, or are they predominantly feeding on juveniles? Also, and I apologise for a biggie, has the average size of recovered beaks altered in the last few years, with implications as to alterations in both whale and squid migration patterns?

Many thanks, (and no worries if you are too busy for a detailed answer).

Phil

 

[Steve O'Shea]

How do the Mesonychoteuthis beaks you have recovered in this, and other, sperm whales compare to the intact specimen you examined recently in size? Are the whales catching older more mature specimens on average, or are they predominantly feeding on juveniles? Also, and I apologise for a biggie, has the average size of recovered beaks altered in the last few years, with implications as to alterations in both whale and squid migration patterns?

You've hit the nail on the head Phil. There are two big questions that I want addressed re squid in the diet of toothed whales:
Is the composition changing over time?
Is the size-class frequency distribution changing over time?

Size-class-frequency distribution is determined by lower-beak rostral length (LRL) (information that I have yet to add). To determine whether the composition of squid in the diet of these animals is changing requires access to one of temporal series of samples, or good archival information. Neither really exist, although there is a lot of information out there (just not a lot specific to New Zealand waters).

Re the Mesonychoteuthis beak sizes, they appear to be larger than the submature female we reported last year, but until I get the LRL's online I cannot be sure.

There's a big IWC meeting in June/July 2005; I've got to try and get all of this information together by then.
Cheers
O

 

[cbarela]

This is extremely fascinating stuff Dr. Steve - I am really looking forward to seeing the pictures of the beaks. I am eager to see the differance of apearance between Archie/Messie/Taningia.

Isn't it amazing that this one whale "sees" on a regular basis what we can only imagine...

Happy Holidays All!
-Chris

 

[snafflehound@work]

So far this is the only one of the 7 with Kondakovia, and the only one with Messie

 

[Steve O'Shea]

... there are more to come; a number with Mesonychoteuthis beaks. I've done the 'easy' ones first (small samples).

 

[Steve O'Shea]

I must have been tired when posting this one first; have edited the identifications (deleted Kondakovia).

The massive beak I am now convinced is from a species of 'Mastigoteuthis' - probably 'Idioteuthis' cordiformis (I'll get a specimen out of the freezer for comparison). The beaks are very similar to those of Pholidoteuthis. The LRL of this beak is extraordinary at 21mm. Pics below (if anyone can shed any light on this).

I am now content with the species list for this particular whale (once I get to the bottom of the Mastigoteuthis (sensu lato)).

Below is a composite pic of the Mesonychoteuthis beaks. Sorry 'bout the exposure problem - am working from a video camera rather than stills with flash.

And these are the lower rostral lengths (ranging 18.5-25, then 2 at 37.5; the one damaged lower beak was also of comparable large size)