Ferry observers on 19 Mediterranean routes see fin whales move their hotspots within weeks

A ferry makes an awkward research vessel. It cannot stop for a pod or divert to follow one. For this question the rigidity helps. The 19 routes are fixed ^[4], so each campaign resurveys the same lines. When fin whales turn up on a different route the next time, the observers' track has stayed put and the animals have not. Running several routes in the same window also gives what the project calls a broad, simultaneous snapshot ^[4]. A single research ship covering the same area would see one patch at a time and blur changes in place with changes in time.

The weak point is detection. Sightings depend on sea state, light, observer experience and how many daylight hours a crossing spends on watch. The published account does not include survey effort or weather by route, so a route that goes quiet could mean the whales left or that the watch had a rough week. The sample also thins out once it is split. There were 707 sightings across three campaigns ^[2], about 236 per campaign ^[1], shared among ten named species ^[2] and 19 routes, and the account does not give counts by species.

The fin whale result is the sturdier one. Sighting totals stayed relatively stable across the three campaigns while the distribution along the routes changed considerably ^[8]. I think a steady count with a moving distribution is harder to explain away than a falling count. A general drop in detectability would tend to lower numbers everywhere, and it would not move the same number of whales onto different lines.

The contrast with striped dolphins is less clean than the project's summary suggests. That summary lists the striped dolphin among species that maintain a relatively stable presence in certain areas ^[7]. The coordinators describe something else. "During the first campaign it was observed more frequently and over a wider area. In the third campaign, however, the sightings were much more spatially concentrated, especially on one of the routes in the Spanish corridor," Garcia-Garin and Gazo said ^[6]. Both statements can hold if the dolphins kept a core area and pulled back into it. Even so, a species that contracted onto one route within weeks is a weak fixed reference for the whales. Loggerhead turtles, the most frequently observed taxon, also fell in number after the first campaign and changed distribution ^[9].

The case for moving protections rests on overlap. According to the project, maritime traffic may overlap with cetaceans and turtles in both space and time, and the data can feed dynamic risk models that combine species presence, traffic intensity and environmental conditions ^[11]. "The aim is to be able to identify more precisely which areas and which periods present a potentially increased risk to marine megafauna and to advance toward a better understanding and management of the Mediterranean marine space," the researchers said ^[12].

The account does not test any existing protected area or ship-strike rule against these sightings. The idea that fixed measures lag behind the whales is therefore an inference from the movement data. For fin whales I'd expect it to hold, provided the shifts survive an effort-corrected analysis and recur in other years. A single June-to-July season ^[2] cannot separate a regular summer movement from one year's conditions. SYNFONY sits inside FLT Med Net, coordinated by Italy's ISPRA, which draws on more than two decades of work with shipping companies ^[10]. That network is where a comparison across years would come from.