maandag 6 april 2015

Hauls 7 (deep sea), 8 and 9

We had a very busy Easter Sunday with three hauls taking place in one day. First was a deep water haul, over 1000 meters deep which was landed on board at around 2am. From this we sorted the blue whiting from the haul and measured and weighed the less abundant, larger species. We then caught a few hours’ sleep before meeting at 9am to resume identifying, measuring and weighing the smaller, more numerous species. Identification can be quite a difficult task due to the similarity of some species who display only very subtle differences as their determining feature. 

Deciding who's who.
Sorting the species...
... and finally some organisation.

This haul contained more interesting species compared to last year’s deep haul due to an increased towing time. Included among the 30+ deep sea species were two deepwater spiny dogfish “Centrophorus squamosus” (one juvenile and one adult female), five black scabbard fish “Aphanopus carbo”, a few snipe eels “Nemichthys scolopaceus” and many lantern fish species from the myctophid family.

Think we need a bigger board...
Centrophorus squamosus” profile.

Black scabbard fish Aphanopus carbo”.

Snipe eel "Nemichthys scolopaceus”.
Myctophidae 'lantern fish' species.
A tray full of horror - "Chauliodus sloani".
"Lampadena speculigera"
"Stomias boa"
A "Pseudoscopelus altipinnis" smile.

Many of these species contain light producing organs called photophores, these are used for communication in the darkness of the deep sea and come in an array of attractive colours!

Blue on myctophidae species.
Pink on pearlside (Maurolicus muelleri).

Even on squid!

Multicolour on unknown squid species.

Haul 8 was fairly standard mostly containing medium sized blue whiting. During haul 9 we targeted a single dense school of blue whiting at around 550 m deep. Unfortunately we just missed the main mark as little was seen entering the net on the netsonde. Instead we used the time to trawl on a scattering layer at around 200 m which turned out to be mostly pearlside (Maurolicus muelleri). Despite the near miss, haul 9 did contain a monster blue whiting of 42cm – not the biggest on record, but not far from it! The large female deepwater spiny dogfish also made an appearance in haul 9 but only as she had been stuck in the net all day, vouched by a crew member who saw her while shooting the net earlier that day.

Monster blue whiting.
Part of processing the blue whiting samples is to determine what sex they are, this is important to understand stock health and productivity. In case you were wondering what they look like, here you are!

The females..
..and the males.
We are now steaming towards the start of our last transect before heading back to the Netherlands - hopefully we will be able to have our last and final haul during this time.

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