Yesterday was possibly the most productive research day I have had in months! Before the sun rose, we headed off to the fish markets in Bitung to look for harvested big fin reef squid.
Normally, these squids are fished very close to shore by artisanal fisherman using lights and hand jigs. The lights attract the squid that are very active feeding during the night. Typically, a plastic glow-in-dark shrimp lure is used to jig for the squid. “Jigging” consists of throwing out a line and slowly bringing it back in with short jerky motions that mimic the movement of a shrimp in the water column until you get a bite.
Upon arriving at the main landing/market on the harbor, we were informed that if we wanted “sotong bunga” (the Bitung term for “sotong bulat”) we would have to wait until at least 6:30 or 7:00 am before those particular fishermen got in. So after a nap in the car, we trouped off to two smaller traditional markets and left with 42 specimens (albeit with a significant amount of haggling!).
Following this whirlwind fish market expedition, we set off to observe and film spawning and egg laying behavior on Lembeh Island. Upon arrival, we found a school of ~15 big fin reef squids engaging in spawning behavior over a bed of staghorn (Acropora) corals! This was extremely exciting as this is the first time I have seen my study organisms in the wild! I think I normally spend too much time staring at reef substrate looking for other things to look around and see them :-). With the help of Tyler (a fellow Barber lab graduate student) and Dimpy Jacobs (the marine biologist at critters@lembeh), we filmed ~2 hours of spawning behavior and egg laying at this site. There seemed to be one mating group that had the most interactions and patterning displays. There was a large male who kept displaying a half white – half brown pattern and flashing it as he neared the coral bed. This is similar to the “lateral silver” pattern observed in the closely related Caribbean Reef Squid (Sepioteuthis sepioidea) that is characteristic of a male guarding a female that he has mated with (Byrne et al. 2003). Squids are extremely communicative through visual patterning on the skin – to signal aggression, use as camouflage, and signal and attract potential mates. While there has been studies documenting this behavior in the Carribean reef squid (S. sepioidea) (read more about this here), this behavior has not been substantially examined in the big fin reef squid, particularly not in Indonesia. Furthermore, as my research and some previous work (namely the work from Ishigaki Island, Japan and Shark Bay, Australia) shows that multiple different species of big fin reef squid occur in the same localities, it will be interesting to observe if there are corresponding differences in reproductive behavior and characteristics! Now to comb through all the footage and document specific patterns, postures and behaviors!
In between these dives, I was frantically trying to take growth and reproductive index measurements on all the squid I had bought in morning. Frantic, not because of all the measurements to be taken, but because I wanted to get them processed so the kitchen could cook it! At every location I go to for research, I collect 50 specimens from the local fish markets and take different measurements to help inform patterns of growth and timing of maturity for the three different species. Second, I dissect out the stomachs of each squid to be taken back to the lab for diet analyses. Normally I find any place I can to do this messy, inky, dissections (e.g. showers, an abandoned table on the beach, piers) without making too much of a mess, but the lovely staff of Lembeh Resort set up a little “laboratory” for me to work on with a large freezer for the samples! I feel so spoiled!
After hunting for some more eggs laid in different habitats in the afternoon on SCUBA, I finished the last squid dissection just in time for a drink and dinner! All in all, it’s been a squidful day.